The ultimate integrated amp.

Tube Research Labs has a new 225 watt a channel integrated that is now available-the ST 225. It is $5500.

TRL makes SOTA very expensive tube preamps and amps($100K+)
They are very excited about this new product.
I had them mod my MF A300 with great results and will get to hear the ST 225 later this month as a friend of mine is going to demo it with his Soundlabs.

Don't know your price range, but this may be something to look into.

I'll say it again.
The Sugden Masterclass Integrated.
I can't imagine any Amp, at any cost, sounding better.

They don't advertise, so they are ignored by the Hi-Fi Press.

What is ultimate to one may not be to someone else and "ultimate" to me means price no object; I suspect there are some extravagant integrated amps I haven't heard of.

All that said, if cost doesn't matter I'd like to have a VAC Phi Beta if for nothing more than to stare at!

At more reasonable prices, Hbarrel gave a nice list and I'll add to that the Musical Fidelity kW500, I am biased though, that is what I use; consider Audio Note as well.

If you want tube then you should listen to Audiomat Recital.

If you like SS then the Nagra MPA (yes there is an integrated version available) should be at the top of your list.

Both are quite expensive but you asked for the best.

I've been doing some similar exploring... what about the Plinius 9200? The fact that it has what appears to be a pretty good phono section is important to me.

Holy moley batman, I just was at Audio Review checking out what the consumer thought of the 383. I was shocked.

Interesting addition to the mix, the MBL.
http://www.stereotimes.com/amp051905.shtm
(It was a slow loader for me.)

Might as well throw in the Mark Levenson 383.

MBL 7008 I wish I never sold it. Also check out the Chord, I have not heard it but my buyer on the 7008 has both now and he speaks highly of both units.

I've just sold ALL my system having to downsize as well.
A SS intergrated amp is what I'm going to go with.
This is based on heresay...
If you're going to stay strictly SS.
In no particular order:
Jeff Rowland Concerto
Blue Circle NSCS
Bel Canto eVo 2i
Edge G3 (85 watts)
Accustic Arts Power 1 (from Germany)
Accuphase
YBA

I think all of the above would make anyone happy.
Which is going to make me happy is my dilemma.
Where I live it's not possible to "interview" any of the candidates so like you I rely on the integrity of those who post here on Audiogon.

This is completly my opnion and I have no idea what "best" means but if I was going to get an intergrated amp I would go for a McIntosh, Cary or Manely. McIntosh has 3 really nice intergrated amps like the MA2275. Cary has 2 nice single ended amps like the CAD-300sei. If you want less expensive the PrimaLuna Prologue II is nice.

Good Luck

What's the rest of the system (the part that's staying -- or "right-sized" as it were:))?