I have had my setup (HD650 -> Valhalla 2 -> Modi 2 Uber) for a couple weeks now and I want to try to make the amp give off a warmer sound. I have heard the Valhalla 2 is probably the least "tubey"/warm OTL amp and I want to see if I could get a taste of a warmer sound. I would like to spend 50 bucks or less on a set of 4 to fill up ball of the valhalla 2's slots. Also, will this void the warranty or possibly harm the amp if i'm parting ways with the stock tubes?
 
If my request is impossible for my budget still recommend other options please.

You may try the Russian 6n3p-ev, and of course, you also need the adapters for it. I like 6n3p-ev better when I use my Valhalla 2 as a preamp to drive my speakers. For headphones, I do listen to my other tube amps more than Valhalla 2.

I also use my Valhalla 2 as a pre-amp with a bifrost 4490 and usb to laptop
I don't know why it's not more common

My experience corroborates what you heard agree with you that "the Valhalla 2 is probably the least "tubey"/warm OTL amp". But the Valhalla 2 serves well as an inexpensive preamp. When I use it as a pream, I do like 6n3p-ev better than other tubes in my hand.

Hey!

Just got my Valhalla 2 a few weeks ago... using JJ E88CC's... it sounds pretty good to me... not crazy "tubey", but pretty good...

I had a. Valhalla 2 and with stock

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