Aside from minor differences, the GX-700 is the rackmount version of the Boss GT-5 floor unit from 1997. As the GX came out a year earlier it doesn't have the few newer effects, such as a silly guitar synthesizer. The GX-700 sits a notch below the Roland GP-100 from 1995 with the Roland having somewhat better features.
The analog-to-digital conversion in the GX is done interestingly at 22-bits and the output at 18-bits, providing adequate all-round resolution with a 100 dB of dynamic range. This is a far cry from the now-standard 24-bit signal path, but it works (in 1999, Boss came up with the feature-compromised, but fully 24-bit VF-1).
You won't have a USB or any other kind of digital interface in a unit as old as this. You do have full MIDI-support as well as a mono effects loop for you to tinker with. Overall, the feature package in the GX-700 is still impressive.
Boxes and Preamps
Apart from the crude and strange Mesa-Boogie model (or ”BG LEAD”), every amplifier sound in the GX is instantly recognizable. In particular I am rather impressed with the Fender Clean Twin and the Peavey 5150 in this thing. Both sound great in their respective categories of clean and very overdriven. Van Halen just flows with the GX 5150 amp model (as it does, surprisingly, on the dirt cheap Zoom GFX-1).
The Roland JC-120 model is punchy as it should be with singing upper mids, and is great for country and jazz. Also, the Soldano emulation in these units is strong. Dial everything close to a hundred, combine with a stack cabinet, add some EQ, and I dare say you have one of the most stunning metal leads of any preamp. The versatile ”Vox Drive” model - a personal favorite of mine from the GT-5 - sadly wasn't present in the unit.
Some of the emulations sound a tad lame on their own, but when boosted with the built-in analog overdrive units their punch is multiplied. One such combination is the Marshall preamp combined with a virtual Boss BD-2 Blues Driver. Another one worth mentioning is an OD-2 pedal going into a Matchless amp, both driven at maximum.
The GX-700 allows you to have simultaneous amp and distortion box emulations, unlike the more expensive Roland GP-100. There are a total of seven distortion types and nine preamps in the GX-700.
The GX-700 also features some decent effects of the usual variety. However, the available six reverbs are quite lifeless. This is where the sibling unit, the Boss SX-700 comes into play with its enhanced audio processing prowess. Try these in tandem if you can find both in the second hand market. The GX reverbs do deserve some praise for including both low-cut and high-cut frequency parameters.
What many don't know about most Boss units is they are rarely useful out of the box. Their patches are often loaded with ear-splitting excess frequencies at specific points in the audio spectrum. This seems to be the case with many single-coil and humbucking pickups. A decent, but limited three-band EQ is luckily included in the GX-700 to fix some of these what I like to call ”Boss Frequencies”. Without these EQ adjustments a lot of people will be turned off from an otherwise great preamp.
The lower-mids in the GX-700 as well as some treble bands are filled with extra sonic marble. Try chiseling off four to six decibels at 250 Hz, 350 Hz, or 3.15 kHz within every patch and the unit's usefulness will be tenfold (the Boogie preamp, in particular, benefits from a heavy dose of EQ).
Mind you, the Roland GP-100 has a much more useful four-band EQ in it – another feature to win you over the Roland side if you're looking for a fun second hand toy. The Boss GT-5 on the other hand includes a very handy second EQ section allowing for some radical sonic adjustments at the expense of most modulation effects.
Tackle the Frequencies
The Boss GX-700 may be from 1996, but in 2016 it's still one of the finest preamps out there. If you have the spare time, hours of hilarity are guaranteed in making patches with this unit. Just make sure you tackle the aforementioned Boss Frequencies with the necessary determination.
Personally I have a mono output going from the GX-700 into an SX-700 effects unit, bypassing the GX's modulation and reverb sections completely. Note: this type of setup is great for live playing, but unacceptable for recording. Never allow your signal to pass through more than one analog preamp. Demand your S/PDIF.