Prima Luna Integrated - EL34, KT88, KT150, Brimar AU - My experience

Thought I would help out some who are considering rolling some tubes ......
Prima Luna Dialog Premium HP Integrated Stereo

Stock EL34 - Chinese I think
JJ/Slovakia KT88 - from ARS
Tung Sol KT150  - yep, these are it, and worth it, do it.. purchased matched from Upscale

First, I have to tell you, I LOVE this amp.  Prior to this, I had a pair of monster VTL Deluxe 300 monoblock tube giants.  In short, the VTLs were less veiled... but the PLs are so musical, believe it or not, better bass! yes, true. and way more fun to own given the tube rolling flexibility.  (I only use the amp in ultralinear, higher power mode).  Oh, and the auto biasing feature - no more burnt fingers or back twists!  BTW, VTLs were a pain and flaky - still loved them and owned them for about 15 years.

The PL comes stock with (Chinese I believe) eight EL34 power tubes.  Out of the box, the amp is stellar.  Why did I try rolling tubes?  Well I have a big stock of power tubes left over from my VTLs.... KT88s ... so after a few months of using the amp as stock... I tried the KT88s.  These KT88s are labeled JJ/Slovakia and BTW, Upscale said to me they won't carry these KT88s from JJ because "their quality control is awful".  Anywho, I put them in anyway. 

EL34 = beautiful.... just a wonderfully musical tube - nothing wrong here - PL did a good job choosing this tube
KT88 = more dynamics, a bit more power, better fuller bass, but something was a bit wrong on the top end.... had an odd edge up there.  Overall I am not sure which I liked more.... the EL34s are perfect but I liked the more dynamics and bass of the KT88.. but their top end ... hmmmm..... I would switch them and therefore hear their strength and say "these are better"... then I would switch and say the same thing.  Issue was there were trade offs.
KT150 =  This is the tube you want.  Compared to the EL34... a bit more dynamics, less veiled, much more power, deeper bass.  Sounds very linear top to bottom.   The only negative of the KT150s over the EL34s... I think the EL34s were a tiny bit more musical... but the KT150s are very musical themselves.  Overall, the KT150s are staying put.  Done.
More to the story.... before I purchased the KT150s I traded emails with Upscale... we discussed the JJ KT88s... they suggested swapping out the front two 12AU7 gain tubes with Brimar CV4003 NOS (made in the '60s).  So I did... and I hated them!  OMG.... they did something to the top that made my ears bleed.  I really let them break in but I had to pull them out as I just couldn't take it.  Now this was with my JJ KT88s.  Upscale responded to me and said I was the only one to complain and describe them as bright.  So... I put the amp back to stock.... listened for a few weeks... then I put the Brimars in with the EL34s ... well OK, much better.. but I still am not sold on the Brimars.  I did learn that my KT88s really do have something bad going on at the top end given these Brimars screamed their issue.  So.... let's buy some KT150s from Upscale.

Note: Upscale said that many like their KT88s over the stock EL34s due to the dynamics and bass improvements so apparently, these JJs have a sonic characteristic that is different than other KT88s.  Maybe.  If all KT88s sound the same, then I can't recommend them.  If they don't all sound the same, then I can say strongly, don't bother with the JJ/Slovakia brand.

I have not tried the Brimars with the KT150s.... right now I have no desire to do so the amp sounds so good.  I probably will try them some day... maybe in a few months.
Anywho... I hope this helps some folks. 

PeaceBruce in Philly