gain can be effected somewhat via tube selection - try 12at7 or 5751

How does it compare to your other amps?

best aspect of this amp is its versatility in being able to handle both 6v & 12v tubes - the various stock tube offerings aren't bad & the nos 6n23p is quite good, but a 1969 6n23p reflektor is even better; try the raytheon 5751 black plate with windmill getter or philips or valvo pcc88; for audeze, maybe try siemens or miniwatt e188cc (nb - not cheap!!). version II of this amp makes tube-rolling even easier.

Thanks for the specific tube recommendations. I have order some tubes and within a week they start rolling.

you're welcome ... telefunken & dutch amperex are also worthwhile to check out, but again, prices can be sky high unless you have a good source. mullards also get a lot of attention, but i don't think it'll be a good marriage with the audeze or the he500.
have fun.

I started with these 5 - so, lets see how big a difference they actually make in subject amplifier:Telefunken <> E88CC / 6922 NOS-6922-TELE6922 / E88CC SIEMENS NOS-6922-SiemensTesla E88CC / 6922 Steel NOS-6922-TESLAElectro-Harmonix 6922 EH EH-6922Electro-Harmonix 5751 EH-5751GP

i don't want to prejudice your opinions, but from my testing, the EH tubes sound 'rubbery' in this amp. i like the russian reflektor & voskhod tubes from the 60's & early 70s - don't care for later versions. i have heard that tesla tubes (gold pins/gold grids) from the 1960's are also very good & underrated. the best european tubes (dutch amperex, siemens, telefunken, mazda) seem to be from the 1950s - 1970s with considerable decline in quality/sonics after this, but there are exceptions.
american 12au7 / 5751 from the same period can be great - look for GE, RCA, Sylvania triple mica black plate, raytheon triple or double mica black plate & windmill getter.
a really good bargain tube is the rca 12au7 clear top which are often found as 'organ pulls' bearing the name of the organ company (like hammond or conn) - used, but testing really strong can be found for ~ $15 or less.
check this out: http://www.ebay.com/itm/6-RCA-CONN-12AU7A-CLEAR-TOP-TUBES-MATCHING-DATE-CODE-1966-TEST-GOOD-STRONG-/180921287078?pt=Vintage_Electronics_R2&hash=item2a1fbfc1a6
hunting for nos tubes can be a risky business - lots of fakes / mislabelling.

I have previous ordered tubes from TubeDepot, and been satisfied with the delivery - so I decided to go with them this time as well. Used to have inter alia some RCA 5814-A in a stereo amp. I liked them. The aforementioned Telefunken and Siemens E88CC are conscious chosen this time. The Tesla just a wild card. The 5751 just to test the gain issue - and the EH just for references (the Sunrise´s ability to change sound signature). I would like to know where to by NOS Voskhod / Reflektor 6n23p - at places other than eBay.

nothing wrong with tubedepot but not the best pricing for nos tubes ... check out their pricing for rca cleartop vs that ebay link i previously gave. voskhod and reflektor, i get on ebay from sellers like ici_electronics or orpheus_2005. i have not seen any 1960's vintage for a very long time and early 70's are getting scarce. for the price of 1982 reflektor/voskhod, i could get 3 or 4 1970's rca cleartop which i feel is a much better sounding tube.
if you get 60s or 70s genuine telefunken/siemens, these are great tubes & i think very good match for lcd-2/lcd-3 (these are amongst the most expensive tubes, typically >> $100 each.
other recommended non-ebay sources are: jim mcshane, vacuumtubes.net, langrex uk (don't know if they are still in business?)
hth,