Pass Labs X2.5 or Krell KAV-280p? WWYD?

Out of curiosity, what price range are you talking about?

It seems as if you are asking an awful lot from a preamp for a small amount of money. Especially if you are talking about a true differential design.

You may be able to get better quality by looking for an integrated amp in the lower price ranges (or even higher). Cost saving could be used on fewer chassis'/cords/cables instead of on lower quality internal components.

Especially since you are already saying that your amp is next on the list.
There are some very good integrated amps on the market these days.

That's just my $0.02.

The price of the two preamps I'm looking at are about $1500.  The reviews I've read on either of them are very positive. Of course they cost $4 K new, so, substantial depreciation there. I did look at an Audio Research tubed pre that has all the features I mentioned, but it was a full thousand bucks higher.  And you are right, I could probably get an intigrated amp for cheaper than separates. But these Legacy Focus speakers are power hungry monsters! I'm hoping for something like a 300wpc Krell or similar.  I'm even considering a D class amp for the sheer power they offer. 

I've thought about a tubed amp, perhaps a tubed intigrated, but if that was the route I was going to take, I'd do the whole thing different. With some smaller tube friendly speakers, perhaps in a smaller room. I might even build it all myself, with a Dynaco kit and speakers of my own design. But for now, I'm on the path of full scale system that can reach near realistic volume and dynamics. The fact is that if I move up from the Halo 3 to either of these preamps, I'm sure I will be blown away by the vast upgrade! So it's a win-win, I was just curious if anyone out there had any real preference for one over the other. I'm kind of leaning toward the Pass Labs just from reviews I've read. 
 
Another thing on my wish list is a Jolida tubed phono preamp, that may be the only tubes found in my setup, and could make a world of difference? 

Wow! I didn't realize the 20/20's were that power hungry. You may be better off with separates then, as not many integrateds offer more than 200 wpc, especially lower priced ones.

If you could find one, and swing a deal on it, the CODA CSib integrated amp would probably be perfect for you though. Legacy Audio loves CODA amps, in fact they had CODA design and manufacturer their Legacy amps back when they were selling amps. I don't think Legacy still sells amps though.

There is a CSib for sale on Ebay, direct from the manufacturer with 10 year warranty, but the price is a bit steep at $4500 (List $6000). Maybe you could talk them down a bit.
The CSib does put out 400 wpc into 8 ohms though, and 800 wpc into 4 ohms. If you haven't heard of CODA, they also evolved from Threshold, just as Pass Labs did. Nelson Pass was the principle designer at Threshold for sure, but CODA was started in the 80's by 3 ex-Threshold engineers. Great amps!

As to your original question, if I had to choose a preamp for around $1500, of the two you mention, I'd go Pass Labs. I do like their amps better than their preamps though.

I'd still be more tempted to stretch a little bit for that Klyne SK6 3.5/P Preamp that already has a killer built in phono stage listed for sale on Audio Asylum Trader asking $2695, w/ $2450 in upgrades only two years ago. You may be able to get him down a few hundred, it's worth a shot.

Happy hunting,
John

Thanks John for your input. I have written a long, 3 paragraph response detailing why I've arrived at my decisions, and spoke about a Pass Labs X1 I'm bidding on today twice!, and twice it has lost it! So, frustrated I'm leaving it at this. Thanks Jafant for your input too, i'd like to hear what you are putting together! I'll update if and when I buy.