I just bought a Audio Research D-90.

Thank you for you help. A.R. made 3 model's of D-90's. They are D-90 (4 pairs of 6550's),D-90-revised (4 pairs of 5581's and the D-90B witch also takes (4 pairs of 5881's.
I'm new to tubes,but I do have a C.J.45mv-a1 that I bought a few months ago. I've been rolling tube and driving tube sellers on ebay nuts with ?'s Is there a book out there what would explain the differant qualities of the tubes?
My Mac pre-amp has 2 sets of outputs, So I'm thinking of bi-amping with the C.J. for mids and highs and the A.R. for the lows.I've got several active x-overs so I thought what the he--.
Any input would be more then welcome. Thank you for your time and trouble,Bill

NEWBEE,
Thanks for the info.What you said about the same tubes in differant amps having differant toneal quallity makes perfect sense.I had to hit myself in the head for being so dense.(By the way,please forgive my spelling.)Each tube is going to sound differant from one amp to another.I guess I did'nt think the ? though.I guess what I want to know is if one model of the tubes I mentioned has a better bass reproduction then the others.I'm looking at using this amp as a low end in a bi-amp set-up.(A.R.D-90)with a C.J.45-MV-a1 for the mids and highs.I've been into stereo's for over 30 years,but I'm very new to tubes. The C.J. is my first and the A.R.,my 2nd. So any input is a great help,Thank You,Bill

NEWBEE,
Thanks for all your help.I ordered 2 sets of tubes today. 8-6L6gc's and 8-6550's.I thought I'd try them both and hear for myself the differents.I'm turning into quiet the tube junkie.My wife thinks I should start selling the ones I don't need on Ebay. She just doesn't get it.I just wanted to Thank You. If you or anyone else has any info, hints or insights that might help me in my new found quest for the perfect tube combo,please write. Thanks,Bill