I have used this with everything from high velocity tube amps to JC 120s to direct into board to...well you name it. It is the best of both worlds, an awesome stage unit (but you need the FC6 foot controller to get around on/off effect changes without a change gap)capable of delivering anything you could want for bass, guitar or general sound application as well as being an amazing studio tool. I have run this direct into recording consoles with only the chains featuring the speaker simulators and I swear it is the most crunchy ass kicking overdriven metal guitar on the earth, or the sweetest little jazz/blues git you could want.
I can get ANY sound I want from this thing and never stop walking away from it shaking my head in amazement.
The Achiles heel on this thing in my experience is the engineering for the instrument input jack. It is VERY vulnerable as it is a jack right onto a circuit board and the input module itself tends to stress the circuit board and damages the solder points. I have repaired this a number of times in the past and just had to retire the unit (temporarily-I hope) because the solder points on the board have deteriorated. If you use this unit for live performance, and use the input jack YOU MUST INSTALL SOME SORT OF STRAIN RELIEF or you may wind up like me, crying over the loss of a good friend. A simple tie-wrap and surface mount holder that you can loop your chord through should suffice. Other than that, had no trouble with it in 11 years.
Greatest rack ever made. I sincerely belive that. Mine just recently died and I went out and hunted down a new one (although I could only find an A3). Can't imagine being without it, it does so much and is so easy to use and so forgiving when it comes to abuse--I love it, can you tell? I would probably pay the original sticker price if that was the only way to find a replacement, even though it's 12 years old. Without a doubt the single best investment I have ever made in gear after 22 years!