Riverstone Audio - 6P1P-EV (6П1П-ЕВ) Tested AND Matched Pair (2pc) - Vintage Vacuum Tubes - Amplitrex Tested - Upgrade for 9-pin 6P1 / 6P1P (6П1П) Tubes - Platinum Grade Pair - 6P1P-EV (6П1П-ЕВ)

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.

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.

good packaging and shipping. products are as described by the seller. some quality vacuum 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.

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.

Combined two matched pairs of 6P1 Riverstone preamplifier tubes with matched Davitu Boutique Soviet 6H8C tubes in Nobsound 6P1 amplifier. This is my first venture into tube rolling. I consider the exercise extremely successful.Highs are much more transparent and Lows are tighter with more definition. Vocals are wonderful.I would recommend spending the money and doing this. You will not regret it.

These are great audio tubes. Well packed and perform much better than the stock tubes.