Here is the tradeoff!! This preamp gives me the best high gain Marshall sound I have heard, but the clean sounds and low gain sounds leave something to be desired. I have been using this preamp for about 4 years. I have just recently started running this unit through a tube power amp (Mesa Stereo Simul 2:90) and it greatly enhanced the sound versus when I was using a solid state amp. I would suggest anyone using this preamp to only use a tube power amp. My band plays rock in which I am using a high gain sound for approximately 80% of what we play. I recently tried a Mesa Triaxis for approximately 30 days to see if I could get a great gain sound, but also get better clean and mild gain sounds (the other 20%!!). I was hoping to replace the Marshall with a preamp that did everything well. The Mesa had fantastic clean and mild gain sounds. The high gain sounds were good (albeit different sounding than the Marshall), but I kept plugging the Marshall JMP 1 back in, amd to me that was it. The Mesa just didn't measure up to the Marshall in the high gain sound (maybe I'm just a Marshall guy). I've heard people rave about the Triaxis, and I liked it for certain things, but to me the one high gain sound on that Marshall outweighed all the good things about the Triaxis, so here I am still owning the JMP-1. I'm going to experiment with a better effects unit to try and enhance my clean sound. I give this unit a 10 for the high gain Marshall sound and a 6 for everything else.
I've used it without a back up for years, and it's never let me down. The output knob is a little touchy between 8 o'clock and 10 o'clock and the input jack loosens up once in a while, but so far neither has needed servicing.
This preamp is great for a high gain Marshall sound, I have yet to hear a better preamp for this sound. However it does not deliver great clean or mild tones. For me, after trying out the Triaxis which does the clean and mild tones great I decided to stick with the Marshall. That one high gain sound outweighed all the other good things in the Triaxis for me (the Triaxis did have good high gain sounds, I just prefer the Marshall sound). I'll just have to deal with not having fantastic clean and mild sounds (although they are usable). Since I use that high gain sound for approximately 80% of what I play, it's not as big a deal to me. If you are looking for complete versatility, this may not be the best preamp. If you are looking for a GREAT high gain preamp and can live without having fantastic clean sounds, this is definately a great piece of gear. This would rate a 10 if the unit had better clean and mild tones.