This is a noise reduction stompbox for guitars. I never really thought about it but I assume it's all analog... Anyway the box is very sturdy, Boss-shaped and sized but WAY heavier.

Well, VERY basic setup with one mere single knob... But does it need anything more?
It doesn't provide the effects loop that its Boss counterpart does, though.

Well, all you expect from this noise reduction box is to... reduce noise, don't you? If such is the case, you can expect to be 100% satisfied. Whether it is a single-coil pickup noise or the typical hiss of a huge distortion box that annoys you, just find the right setting and you'll get your guitar sound -- your WHOLE guitar sound, NOTHING BUT your guitar sound. Hard to find a setting that will suit both your clean and saturated sounds though, so try to get a setting that is relatively hiss-free when distortion is off. It proved efficient in taming successively a SansAmp GT2 in Mesa simulation mode, a Zoom Tri-Metal (not too difficult though, this one has an integrated noise gate but the Decimator still removed whatever was left of noise), an EHX Metal Muff and a Big Muff boosted by an overdrive.
Since I don't use a proper amp I couldn't test it within an fx loop.

The Big Muff Pi is a reissue fuzz box/sustainer made in Russia. Its a very different manifestation of the classic in appearance, in a sturdy black metal casing with chicken beak knobs, and comes with a cool wooden storage box. It has 1/4" input and outputs, which are annoyingly on the opposite sides from where you would expect them to be, like other effects boxes.

Dialing it in is pretty easy and self-explanatory with just a gain, tone, and volume knob. I never used the manual.

I have to admit, I don't understand what the fuss is all about with the Big Muff, or fuzz pedals in general. Its thin, hissy, buzzy, fuzzy. It is not thick, pleasing, or even musical sounding to my ears. I played with it for a while, using my Les Paul style guitar through a small tube combo, and found no usable sounds. I don't think theres anything wrong with mine, I just think the overall tone of it makes me cringe.

I will stick with my TS9 Tube Screamer for creamier sweet sustain, and other pedals for more heavy distortion. This Big Muff just does nothing for me.

Digitech's RP line are computer chip driven multi-effects floor units boasting effects like flanger, phaser, rotary speaker, tremolo, envelope filter, chorus, delay, and reverb along with amp simulations of popular amps. Some have an expression pedal for assigning an effect to like the RP300A.
The RP300A features 1/4" input and stereo output jacks, headphone output, jam-along 1/8" input, and it includes an AC adapter to power it.

Let me just say, the presets might impress you in the store, but when you get home and really start playing you will want to start creating your own presets, which is fairly easy. Don't be deceived by the advertising, you can only use one effect at a time and not 12, but fortunately the effects are seperate from the compressor, delay, and reverb; so for example you can dial in your compressor settings, then your amp model, your effect like chorus for instance, then your delay settings, and then finally your reverb. But using chorus and phaser at the same time; you can't do that.

The effects are fairly good, maybe not as realistic as if you had individual stompboxes from Boss or DigiTech for each effect, but they certainly aren't junk by any means. They are quite usable, and they have up to 4 parameters to edit for each effect, which can be tedious but gives you more control. If you want LESS paremeters to edit and more simplicity then maybe the RP200 or 150 is for you.
I played a handful of instruments through this, mostly a Fernandes LP Junior style guitar and a custom Telecaster. I dug the clean sounds of the Blackface model with my Tele, and the Rectified model for distortion. I soon became addicted to swirling delays and whooshing flanger and phaser effects, and the spacey vintage vibe of the rotary effect. I was on an effects high for weeks. The compressor definitely comes in handy for getting even sustain as long as you arent heavy handed with it.
Ultimately, the amp models can sound a bit synthetic, and the effects don't sound analog, they are fairly obviously digital, but I think running into a good tube amp would greatly improve the sound from what I was playing it through: my old solid state Peavey combo.

I would imagine the speaker cabinet models would help in making this sound better for going direct into a PA system, but I still wouldnt want to unless I had to. Some comment it becomes thin.

The Snarling Dog's Black Dog is an overdrive pedal. Its built like a homemade pedal and not not mass produced ones, with a 2 piece sheet metal angled box, generic push button, and classic chicken beak knobs for volume and gain. It also has a switch for "attack control" that lets you choose "snarl" or "bite". Fun, fun. But the coolest thing about this pedal is the dog's face staring back at you whose eyes light up red when you switch on the unit.

Its pretty simple to operate; no eq, just a volume and gain knob, and attack switch.

I like this pedal, it has a very classic sound to me. Its got more bark to it than my TS9 tube screamer, though not as much sustain. I find it perfect for nailing that AC/DC sound.
I eventually get a bit bored and it feels kind of like a one-trick-pony since I can't get creamy sustain for soling like I do from the TS9, and its not quite as warm.
But, since it has true bypass, where you can turn it off and its like its not even there (why can't more pedal makers spend the time to do that>!) then I like to keep it right there in my signal chain for that classic british bark once in a while.

The DOD Grunge pedal is a bit misnamed, it can maybe create a "grunge" sound for you if you play with it, but it is mostly a pedal for metal lovers.
Its a fairly typical distortion box, 1/4" input and output, red led, ac adapter input, in a sturdy metal casing with a cheap plastic stomp button and battery cover like all DOD boxes, when will they ever learn not to use plastic? It has 4 knobs; "loud", "low", "high", and "grunge" (which means 'gain' in DOD-land for this pedal anyway). Its pretty simple to use.

I was a bit suprised at how much control the "low" and "high" knobs give you. You can't just max this thing out and rock out like some guitarists are tempted to do, but you will equally lose out by just leaving the EQ at 12 o'clock. You can add a ton of thick low end to your palm muting riffing with the "low" knob without it getting muddy as quickly as I would expect, and the 2 eq knobs seem a bit interactive. It adds a lot of versatility to this pedal.

This pedal will probably elicit a 'love it or hate it' reaction from most guitarists. I do like the meaty crunch of it and the amount of gain possible, but it does start to sound a bit "synthetic" to my ears and never really sounds "warm". Its a very raw, grating distortion. It might be cool to play Pantera riffs, and detune to play newer metal, but..... I would never play prettier music like indie rock or even screamo with it. Its just to nasally and over the top. I go to this pedal when I want super aggressive distortion for metal type playing. I have the sense to reach for my Tube Screamer when I want creamy overdrive/distortion for lead/soling, and my Snarling Dogs Black Dog when I want a more classic sound.

I hate the sound of it with the gain turned down, its not very versatile in that regard either.

The TS9 Tube Screamer is an analog distortion/overdrive unit. Mine was made in Japan, and it has the characteristic green paint, 1/4" input and output jacks, red led light, and ac adaptor input, all in a rugged metal case good for stompin' on.

Its a super simple pedal to operate, just 3 knobs; "drive", "tone", and "level" so its pretty self explanatory. Having a single tone knob rather than seperate "high" and "low" makes it easier to achieve a more "transparent" sound from the TS9 since you can just park it right at 12 o'clock.

In itself, the TS9 only makes one sound, but is good at it. Its not a super hi gain distortion, but will give you a stinging lead tone for soloing and plenty of balanced, sweet sustain depending on what guitar you are using. I play most an Ibanez Ghostrider which is built like a Les Paul with mahogany body / maple top and set neck.
Its not a thick, beefy overdrive, but its not thin or buzzy. Its sort of a sweet, middle of the road, mild distorion, or even just a gentle overdrive if you dial it in low. Its fairly versatile in its range, but its character remains the same through its spectrum from mild overdrive from medium to hi gain distortion.
One thing I like to do with my TS9 is use it as a boost to push a tube amp like my small Epiphone Valve Special into greater breakup.
I also get really cool results by purposely dialing in distorted sounds from the TS9 and then backing off the volume on my guitar to clean it up, like going from the solos in "Black Magic Woman" to the verses which are obviously cleaner, or just to get a clean sound with more sustain than usual.

This is a clean boost pedal.. 1/4" true bypass.. I'm assuming this is an analog effect.. (durrr) Definitely NOT rackable... bulletproof construction.

Uh..1 button. 1 Knob. Wow. No manual necessary. Anyone can do this. It is a clean boost.. especially on cleans.. really enhances distortion if used in front of a dirty amp.

Mmm..really clean. True bypass pedal.. really quiet. Great deal for 80 bucks. Does not add artifacts, fuzz or anything else truly.. it WILL enhance distortion because it is fattening up your signal. Adds LOADS of beef to my Strat with a Dimarzio HS-3 stacked humbucker in the bridge. Using this and a Keeley TS9 in front of a Voodoo Lab Preamp absolutely SCREAMS. People cannot believe the metal tone I get with a Strat with single coils. I can get that grind from Godsmack "Keep Away".. with an even heavier/fatter lead tone.. knock off the pedals, flip to the neck pickup and and I have nasty blues... hit my clean channel and I can comp Stevie Ray Vaughn. So.. using it as a pickup booster for humbucker tones can make your Strat even more versatile. To really get this as a clean volume boost on a dirty amp..You have to run it in the effects loop. My rig does not have one.. so.. I just use it for signal fattening. Either is good.. it is a very clean effect.
More on the issue of volume boost versus gain boost. In the front end of a dirty amp this will NOT give you enough db gain to use as a boost for solos. In front of a clean amp, then yeah.. it will noticeably bump it up. With distortion you MUST run it in the loop.. (between your preamp and poweramp stages) to get a usable real solo boost. If you are just looking to increase your distortion or fatten your signal, run it into the front end.
Use this with the Strat mostly, but also with Les Pauls, Tele's, other humbucker guitars if I want to go over the top. I use this with one particular Yamaha electric with JB's in the bridgee..and I get a really close approximation to Eric Johnson's old tone (shockingly enough. It gets that chunky Fuzz Face meets Plexi fatness).
Nothing I hate about it! (except that it adds some noise.. but way less than even my Keeley TS9...

The POD Pro is basically the same amp modeling technology and effects contained in the POD unit but contained in a rackmount unit with actual knobs so editing presets on the fly is much easier. It has the capability to be controlled by a floor footswitch, though I never forked out the money for it and I don't play out so I don't require that kind of control.

On the rear of the unit it has stereo outputs to go to power amp, footswitch jack, effects loop input and output, and a single guitar input on the front.

Its pretty sharp looking, sitting in a rack all lit up.

Editing the presets is super easy, its as simple as twirling knobs to dial in the desired amp model, gain, eq, and effects. Fine tuning the paremeters on some of the effects would probably require the foot controller but the stock settings aren't bad and satisfied me. I actually did read the manual which is unusual for me, it was very informative and saved me some time tinkering with it.

I played a couple of humbucker equipped Les Paul style guitars through it, while running it into a samson 120 watt power amp, then into a crate 2x12 combo amp I turned into a speaker cab.

The amp models are the typical Line 6 stuff, sometimes you are suprised at how close they get capturing the "essence" of a particular tube amps sound like the Dual and Triple Rectifier models, but since modeling technology is not quite capable of emulating the dynamics and behaviour of tube amps- some models don't stand up to the amps they seek to imitate at all. I LIKED the sound of the "blackface" model but it doesn't actually sound like a Fender.
If you are into heavy riffing, you will LOVE the "Insane" model. Think of a Boss metal zone morphed with a typical Marshall hi gain sound, and there you go.

The effects are quite good, not as good as the Flextone III I had owned previous but the POD Pro was of an older generation so it shows Line 6 is contantly improving their products. Playing in true stereo makes a real difference here though, the effects don't come alive nearly as much otherwise.