I agree that the preamp may not be the problem as far as boomy bass goes but it can indeed add to the problem. I would suggest you look at Tube Distinctions Soul Mate Preamp. Not just because I have one for sale here on Audiogon but because it is a great match for tube amps. I have used it with Atma-Sphere M60 mono-blocks to great success. The bass is tight and it is very fast and neutral. Check out their web site by Googling Tube Distinctions and then clicking soul series. Good luck in your quest!
