Riverstone Audio - 6P1P-EV (6П1П-ЕВ) NOS Tested-Matched Pair - Upgrade for 9-pin 6P1 and 6P1P (6П1П) Vacuum Tubes - Amplitrex Tested - Platinum Grade Pair - 6P1P-EV (6П1П-ЕВ)

Upgraded my rockville blu tube amp 6P1 with these 6P1P-EV. Sounds much better. Cleaner tones. Richer sound.

I bought 2 matched pairs of these to use in the Nobsound 6P1 amp, they are a nice upgrade. Frequency response is flatter and improved bass and clarity. + having a matched pairs in a parallel amp is important. I did have to message to seller to unlock the purchase limit to buy 2 pairs, which was a little annoying, but I understand why they have it in place. These really are the best available tubes for that amp and I recommend this upgrade.

the tubes (2 sets) were used to replace Chinese analogs in 2x6.8W stereo class A amp purchased on Amazon. The manufacturer, located in St. Petersburg, Russia, is quite respectable. Moreover, the "EB" suffix means extended life (5000 hours and more) and improved mechanical stability/reliability. The tubes are very likely to be military-grade. It seems that the sound improved. The packaging was very nice and professional.

Amazing sound upgrade! You think the stock tubes sound great on the Nobsound 6P1 amp? Wait until you try these on for size! Well, I rolled the tubes in my Nobsound because I thought something was wrong with them. The sound started to fade and there were various clicks and pops but I think the tubes weren’t fully run in. Trying these guys out though, the tubes “bloomed” in about three weeks. You’ll know when your tubes are fully run in. My god, the vocals are amazing on valve amps. Listening to the luscious chorus of Beranger’s “Country of Mine” almost made me orgasm. Even Haley Reinheart’s rendition of “falling in love” will make you fall back in love with your music collection. Whether you roll with Meute’s rendition of “you and me”, or the wonderful Piano solo “Hammers” by Nils Fram, these tubes surely wont disappoint.

Got two separate pairs and neither one works. Even confirmed that it is the correct one for my amp.

Very nice job Riverstone Audio! Nicely packaged, love the measured plate current and transconductance values shown for the pairing. Unfortunately in my case the Russian 6P1P tubes caused a significant deadening of the highs compared to my amp's OEM tubes. Had to return. Note to those who have amps with LEDs under the tubes to add color - these tubes are black on the bottom preventing LED lighting from shining through.

If you're looking to upgrade the tubes in your preamp, spend the extra bucks and get these. This company goes above and beyond to provide quality, matched tubes.

Wish I hadn't waited several years to experiment with tube rolling. I just replaced the stock Chinese tubes in the Monoprice 50W Hybrid Tube Amp with these from Riverstone, and there was an immediate and obvious difference in sound quality. Totally blown away. I though maybe different tubes would just be snake oil placebo, but these make the sound so much more transparent, lifelike and 3D. Best sonic upgrade I've ever experience for so little money.