I can tell you basically everything about the GSP series. I have been using Digitech gear since I was 16 years old (the processors) and now am a full time clinician for them. I know these things inside and out cause well... its my job! lol
The GSP procesors started out with the GSP21. Then they went to the GSP21 pro then the GSP21 Legend. They did make a GSP Legend II for a while as well. Then they made one of the coolest pre amp processors around (in my opinion of course) called the GSP2101. This was a 2 space rack unit that used the S-Disc processor. They then came out with the a limited edition processor called the GSP2101 LE that came in a variety of cool shiny colors (lol) and offered dual S-disc processing which allowed for preset morphing. This would allow you to have a preset with delay and reverb trail out over top of the next preset you switched to giving it a "cross fade/studio feel". The GSP2101 Artist processor also came out which the LE could be upgraded to. All this did was give artist presets as well as upgrade the tuner and give you inteligent pitch shifting.
When the 2112 came out, they took away the XLR outputs (along with that secret cool cabinet emulator button on the back that made the 2101 sound extra cool). Then they came out with the 2120. From the 2101 to the 2120, each processor used the Control 1 foot controller. I was never too fond of the 2112 and 2120's distortion sounds. Maybe it was because I knew my 2101LE so well and had favorite tones, maybe it was because I could no longer use the balanced outputs.... who knows. I know Whip from Queensryche loved the hell out of his 2112.
I used the hell out of my 2101LE until the GSP1101 came out. I sat with my 2101LE and the GSP1101 side by side and was able to get my EXACT distortion sounds as well as SO MUCH MORE on the 1101. This amazed me because the 2101 used tubes and the 1101 does not. BUT as I came to find out, there is good reason that over 50 pro level (and I mean ROCKSTAR level) guitar players now use the 1101 in their setup. The new micro processor called the Audio DNA2 chip. The 1101 has 2 of these in it. The Audio DNA 2 processor is literally 400x the power of the standard micro processor on the market. Most companies dont have a big enough R&D budget to design their own micro processor and buying the faster ones on the market just ups their overall cost on the unit making it more expensive for the buyer. Sooo they all pretty much stick with the same micro processor which gives them all the same limitations to work with. Digitech however is owned by Harman who also owns, Lexicon, JBL, Soundcraft, Studer, AKG, DBX, BSS, DOD, Infinity Speakers and quite a few other brands. They have a VERY large budget for R&D. What does that have to do with anything? Well.... try comparing an Atari 2600 game system to a PS3 or X-Box 360 game system. :-) NO COMPARISON. What made the later so much better? The POWER of micro processing to be able to handle a million times the information in a split second. Relate the graphics now to audio. In the beginning graphics on video games SUCKED. NOW however they look like you could walk into the TV they are so real. It all comes down to how much power you have to process information. The more power you have, the more information can be processed in a quick enough time to where it becomes usable in a guitar processor. With the Audio DNA 2 chip, it now makes amp and cabinet modeling a REALITY. You can play an amp model and roll down the volume knob and it will clean up like a real amp should. It reacts dynamicaly to your picking. Older amp and cabinet models sounded ok at best on volume 10 but when you rolled the volume knob down they broke up and could not react as an amplifier does. Also, older amp and cabinet modeling only gave you one volume whether you picked lightly or heavily. Basically it was pretty unusable.
When I do clinics and most of my shows I use the GSP1101 DIRECT into the mixing console. I have people ALL THE TIME coming up and asking what amp I am using. Its not just me either. When Queensryche goes over seas, they only bring their 1101's and Control 2's for their fly rig. NO AMPS OR CABS. They go direct.
The GSP1101 also has a cool preamp loop feature that allows you to plug your amplifier into it. You can then switch back and forth between your amp's preamp, and the internal preamps on the processor. When you use your amplifier's preamp, it does not just bypass the 1101's preamps, it takes them COMPLETELY out of the loop. You NEVER run more than one preamp at a time. Most processors MAKE you run through some sort of preamp when you just want to use a reverb or something in it. This COMPLETELY changes the tone of your rig. Running 2 preamps at a time makes it so basically the processor takes over your tone. With the GSP1101, it is meant to either supplement your tone or be the center of your tone but not change your complete tone unless you want it to.
You get Lexicon reverb and delay, a WH4 whammy, 3 different wah pedals, 2 different compressors, 2 different noise gates, over 15 distortion pedals, over 40 amp and cabinet models, just about every effect that digitech makes. There are literally over 1600 different combinations of amps models, cabinet models, and effects you can do. PLUS it has 1/4" outs, XLR outs, AND a USB output that makes it so you can use it as a control interface for recording into any recording software (other than Pro tools of course).
And the Control 2 is ANYTHING but chinsy. It is a SOLID bent metal controller with vaccuum style stomp buttons and a full size expression pedal. It connects with CAT5 cable which means you can run ANY length of cable from the 1101 to the Control 2 and never lose signal. It has 10 buttons plus bank up/bank down, tuner, and tap tempo buttons. Look at this picture:
Does that foot controller look chinsy? Hell I played outdoors at Summerfest in Wisconsin and it rained for 2 days. We had an inch of standing water on the stage. Each night I held the Control 2 up and DRAINED the water from inside of it, dried it off, and used it the next day. I am STILL using the same one on the truck for my gigs and that is 2 weeks each month most times in scorching heat. I just got off the last tour where it was 105 and 103 degrees. Lemme tell ya, if something is going to malfunction, its gonna happen in heat like that ESPECIALLY when it is sitting on a BLACK METAL stage collecting even more heat.
All I can say is that the tone is SOLID. AND you cant beat what your getting for the price. Hell a WH4 and a Lexicon MPX300 would run you more than the entire processor costs. I used the RP500 and the GSP1101 as my MAIN preamp tones on my new album I just got done recording. There has ALWAYS been a gap between tube amp and digital modeling. UNTIL NOW. It only took time to finally get a micro processor fast enough to handle all of the information. And even if you dont use the amp and cabinet models of the GSP1101, having the ability to run Lexicon reverb and all the other effects in pre and post set up without changing your current tone is worth the $499 for the unit and $299 for the controller. AND you dont NEED the Control 2 to use the 1101. You can use ANY standard MIDI foot controller to control the unit. Its just the Control 2 was designed SPECIFICALLY to work with the GSP1101.
But hey.... what the heck am I ranting about. I just got off my tour for this month so this is my time off! lol While at the amp show though I did get to play on a processor I thought sounded incredible. It was by a company called Fractal Audio. I LOVED it cause it sounded like the GSP1101. The amp and cabinet modeling was amazing. You know the main difference? The Fractal Audio Ultra is $1999 the GSP1101 is $499.... you choose.... lol
Keep rockin guys,