I have a pretty nice little stash of new and NOS tubes, most of which I have not had an opportunity to try. Now that I have a couple of tube preamps, I was wondering which one you folks thought would be the best for trying out various tubes. Ideally, I'd be looking for a preamp that allows the characteristics of the tubes to be heard (or not heard, as the case may be), and that does not add much coloration of its own. Ease of tube swapping would also be an appropriate consideration. Here are the tube preamps that I have to chose from: Aguilar DB 680 Aguilar DB 659 Eden Navigator Alembic F-1X Demeter VTBP-201s Chandler Tube Drive Tube Works Blue Tube Alternately, I could use one of the following heads: Eden VT-300A Aguilar DB 359 Trace Elliot V8 Mesa Boogie Walkabout The Navigator has never seemed very responsive to tube changes, so I am thinking that it is not the one to use. My only other semi intensive tube rolling was done with the Walkabout, and I certainly could hear small, but subtle differences in every tube. The 680 is a great pre, but it's got three 12AU7's and two 12AX7's, so it might be difficult to nail down just which tube was imparting which characteristics. The V8 has seven 12AX7's, so that's not going to help! The Chander/Tube Works is nice, in that it is a fairly simple circuit path, and from past experience (with the Chandler), you really hear major differences between tubes. The downside is that these units are not designed primarily as bass preamps. The 659 has been one of the preamps to respond the most dramatically to a tube change, but it does seem to have its own character. I guess I am leaning towards the Demeter or the F-1X at this point, with confirmation testing on the Chandler. Any thoughts? If anyone is interested in hearing my thoughts on a particular tube in a particular amp, I can try and post a list of the tubes on hand. Later, Tom.