I have an Audio Research VS115 amplifier that uses 8x 6550C (or KT88 or even KT120) and none of these are inexpensive anymore. One of the tubes sparked and probably took out a resistor or something - the whole amp is dead. I haven’t had a chance to check, or send for repairs. And I moved a couple of times and I don’t know how many of the remaining tubes survived. A matched octet varies from $700 to over $1000 and they are all Chinese or Russian tubes (except JJ). I was using the Audio Research to power Magnepan 3.7’s and they were OK, but the Maggies, like some of the Stax headphones/earspeakers need as a lot of power to really come to life.And not just a question of volume. It’s like regular vs balanced cables. I had a Sennheiser HD600 for years with the stock cables and was happy with them. Recently after watching a review of the Woo audio tube mini I decided to try out some cheap balanced cables for the HD600 with the Ifi Zen DAC - WOW, not only more detail, but a lot more pleasant to listen to…
