Features

The GNX4 combines dozens of effects with an eight-track digital recorder, USB and MIDI interface, drum machine, and some pretty trick computer software (Pro Tracks Plus from Cakewalk).

With some tweaking and correct connections (to amps and so forth), the GNX4 sounds great. A few users have complained about this and that regarding the sound quality live--chances are, they just have not explored the various setup options (Speaker Compensation, EQ, and so forth).

Amp Modeling
After owning the GNX4 for almost a year, and comparing it to other amp modelers I own or have tried, I would say the GNX4 amp modeling is middle of the road (see SuperModels below). As with most modelers, if you like the heavy-metal rectified, high-gain sound, the GNX4 does pretty well. Where it lacks IMHO is in more subtle amps and applications. Though you can get a clean sound, the clean and blues-type amps just are not quite right. They miss the warmth, thickness, and sustain of a good clean tube amp.

I also find it a bit tedious to setup an amp. The GNX4 offers cabinet (?) EQ, something I have not mastered. Luckily, Guitar One magazine provides a variety of GNX4 settings each issue. I often use these as starting points, especially EQ- wise. I prefer the much simpler approach of the VAMP or VOX Tonelab. Turn a dial to select an amp with separate controls for EQ. The GNX4 approach of multiple use buttons is fine if you're sitting at home and have some free time, but is a drag when you want to quickly select an amp and cabinet.

Effects
In regards to effects. This is where the GNX4 beats most other modelers. I am very disappointed with the POD XT Live and its supposedly great 80 effects. Unless I am missing something, and perhaps I am, the GNX4 categorically kicks the POD XT Live's butt in this regard. (Note: there are a few great POD XTL effects.)

The WAH and pickup selector settings are very useful, though to be honest, I don't use them much.

The compressor functions as well as any I have tried, something I cannot say for the myriad of stompbox compressor models of the POD XT Live. It is not just a threshold gate/cuttoff. It really seems to compress the sound and if you set the gain high, each pick of a string explodes--just like a good compressor should do. My only negative comment regarding the compressor--it does not appear to be footswitchable (on/off).

The distortion models, especially the Boss DS version sounds great. I own the Boss DS-1 and cannot tell much difference between the GNX4 model and the original when a/b switching between them.

The modulation effects blow away the POD XT Live, both in quantity and quality. The GNX4 offers the standard chorus, flanger, and phaser. They all sound fine. In addition, the GNX4 offers a triggered flanger, envelope, phase shifter, synthtalk, etc. I find applications for virtually all of these effects and no other box that I am aware of provides this quantity and quality of modulation effects.

The delay variations are good. I am not super thrilled with them, but.....

The reverb variations are also good. Again, nothing outstanding, but plenty servicable.

Looper
Once I got this to work, well it is a killer. You can spend big bucks just for a looper and its thrown in with the GNX4.

Drum Machine
Fair to good. Serves my purposes, though this an area (drum machine, drum tracks) that I am sorely lacking in talent and technique.

On Board Recorder
It's okay. Not great. The sound quality of the onboard recorder versus recording the GNX4 using the computer is night and day. Perhaps I am doing something wrong, but the onboard recorder sound quality is not great. I use it to capture riffs, ideas--perfect for that. It's also provides the looper function. Oh, and the recorder eats Flash cards quickly. Sound files are rendered as WAV files so they are huge.

Connectivity
No multi-effects box that I am aware of does a better job of acting as a mixer, providing line ins, mic in, two sets of line outs, speaker compensation, USB, MIDI, and so forth. Easy to setup, easy to use, perhaps the most important feature for my use. In comparision, the POD XTL does not have stereo line ins, does not have balanced line outs, does not have two sets of line outs, and does not push MIDI note data (for recording) through its USB interface. The BOSS GT8 does not provide two sets of line outs and does not have USB.

X-Edit
The GNX4 is bundled with XEdit, the tool used to create, modify, delete, and store GNX4 presets/patches. The tool is very well designed, is relatively easy to use, and provides full access to the inner workings and capabilities of the GNX4. It is complicated, only because the GNX4 offers so many parameters, effects, and so forth. It takes guys like Mike-Guitar3456 to fully understand and leverage the power of this tool and the GNX4.

Complaints
I have a few complaints. The tuner can be difficult to engage (must press two footswitches simultaneously) and it is not super accurate, IMHO. I much prefer my Boss TU-2 and POD XT Live tuners. I would like better amp modeling. The onboard recorder is great for quickly recording ideas, but the sound quality leaves something to be desired. Would like the JamMan feature of earlier GNX4s. Does not appear that the GNX4 X-Edit application works on workstations that are not connected to a GNX4. Finally, would like a little more mixing control.

Bottom Line
The GNX4 is perhaps the best all-around multi-effects box available today. As advertised, it is a Guitar workstation--the Swiss army knife of multi-effect boxes. Its amp modeling is not as good as the POD XT Live or VOX Tonelab, especially for those of us who don't do a lot of heavy metal (see SuperModels below). However, the rest of the package is superior--connectivity, onboard recording, onboard drum machine, and the quantity and quality of effects. The real bottom line: All of these multi-effect amp modelers require lots of time to completely figure out. Yeah, you can use them right out of the box. But you must spend lots of hours to get the most out of these boxes. Unfortunately, I don't have the time to invest like I should. Frankly, if all you are after is great sound, any of the top boxes (VOX Tonelab, POD XT, GNX4) will work just fine--you just have to put in the time.

The number of features and specs are too numerous for me to describe here. Consequently, I will leave that up to the Digitech GNX4 Brochure (PDF).