I have an HP as well and have used those NOS Mullards (the 8136 variety?) on my front end as well. Huge difference. Worth the $$ IMO and we are talking $120 per tube.
Theoretically, you can put 8 different EL34s in there and due to the PL self-biasing, it should work fine. but even Upscale Audio (kevin deal part owner of PrimaLuna) doesn't recommend this at all. I dont know the specifics, but makes sense on a common sense level.
@newbee makes a good point about trying modern production tubes before the greater expense of a full Octet of NOS tubes. But sometimes I want to take my upgrade climb 2 levels, not just one. The new production tubes get you 1 level. NOS gets you 2-3 levels higher.
To save some money and intermediary steps, consider going straight to NOS if you will be using that amp for years to come. If you get the 8 modern tubes, listen for a month, then desire to go up to the next level, then you've got 8 tubes on your hands to have to sell.
IMO< any upgrades to the PL HP integrated helps the whole system. It think of it as a great foundation/blueprint to build on with tubes specific to your system and room.
Theoretically, you can put 8 different EL34s in there and due to the PL self-biasing, it should work fine. but even Upscale Audio (kevin deal part owner of PrimaLuna) doesn't recommend this at all. I dont know the specifics, but makes sense on a common sense level.
@newbee makes a good point about trying modern production tubes before the greater expense of a full Octet of NOS tubes. But sometimes I want to take my upgrade climb 2 levels, not just one. The new production tubes get you 1 level. NOS gets you 2-3 levels higher.
To save some money and intermediary steps, consider going straight to NOS if you will be using that amp for years to come. If you get the 8 modern tubes, listen for a month, then desire to go up to the next level, then you've got 8 tubes on your hands to have to sell.
IMO< any upgrades to the PL HP integrated helps the whole system. It think of it as a great foundation/blueprint to build on with tubes specific to your system and room.