What sound diff. can I expect from PrimaLuna EVO 400 pre and power amps VS an EVO400 int.

Since you're open to used, I'd look into something on this level

Manley Chinook tube phono preamp For Sale - US Audio Mart

tubed, good reviews. I demoed one in my setup.  These can be had for less, if you're a negotiator or patient/ready to pounce on better price.

The Mani is great for what it is-a $150 phono amp. I had one as a backup while getting my proper unit repaired.

"I am using a Willsenton R8 integrated Chinese-made tube amp with KT88 tubes "

The PL will have noticeably better construction details/parts, but It may not be leagues "better" in SQ?

Based on things I've read, it's a decent amp-for the price. Just how much "better" the PL integrated would be something between you and your ears?

That's where separates AND your wallet will make a significant difference.

The bad news you should already know is it always adds up to the sum of ALL the parts.

The 400 Evo I would-not recommend  ,you loose a lot of resolution in the volume pot if it’s a round silver $20 alps type  , several  several tech friends build preamps from scratch ,that is the 1st thing they discourage  what good is have a well built machine and then at its volume attenuator you have junk ?

I soldAudio for years you want either a relay type ,or resistive ladder type , a separate transformer type are excellent also but-very expensive.

These types  take up. More space and much more expensive to build, these alps type are just plastic wipers with a conductive coating ,you loose a lot of low level detail  with these cheaper type .that's fine for a $1 k or less  preamp , also your power supplies are very important to keep the performance from drifting especially when the volume is turned up,or things get complex.

Thanks again.

Years ago, when I was younger, and a little dumber, I got my pilot's license. Flying small, single-engine aircraft was not really exciting, so I started jumping out of them. That was one hell of a lot more exciting.  I logged over 32 minutes of freefall time before my then-fiance made me stop.

I equate the effect of this OCD quest for better sound on my bank account to a jump from 9800 feet with the resulting 45-second freefall. In both instances, there is a very rapid drop.

I think the prudent move is to acquire a good tube phono stage first and evaluate its impact on my system. The preamp or amps can wait until I can evaluate the effect of that component. 

Time will tell.  

My phono stage is a Modwright 9.0x and I'm very happy with it.

Ausioman58: Thank you for your comments. That goes into a level of detail far beyond where I usually delve. Is it only the EOV 400 with that issue, or do other PrimaLuna amps have the same problem? 

Are there other tube amps and preamps in that general price range that you recommend? 

Of course, I am interested in the sound quality above all else, but when I spend a wad of cash, I expect longevity as well as performance. In an age where competence is a vanishing commodity, perhaps I am asking too much.