Earlier this year I went ahead and invested in some EML 45-v4 tubes and matching octal bases. I swapped out the bases, rewired everything to use the center tap, and removed the resistors that connect to the trim pots. I checked all the resistance values and they are very close to spec. Haven't checked voltages yet because I don't have a good way to set the amp up to test it safely. I'll have to think about how to do that. In any case, when I first turned it on I was a bit nervous it would explode, but the filaments just warmed right up. Some nasty hum in both channels was completely removed by adjusting the pots a bit. The low-end buzz is completely gone, dead silent. There is the tiniest "hissing" noise (high frequency) with my ear a few inches from the speaker.
I threw on some music and sure enough it plays just beautifully. *Much* more powerful right out of the gate than the Sophias I was running before. I hear they have an extended break-in time, so I'm going to run them a few hours a day and then redo my A-B comparison with my first amp love the Sugden A-21ap. For reference, they are playing through Decware Zen Open Baffle speakers, which probably are about 95db sensitive, with a pair of Vandersteen 2wq subwoofers.
My initial impression is that the soundstage is very nice, but not as wide as the Sugden. The highs and upper mids are definitely awesome, crystalline and just sort of floating in mid-air, smooth and beautiful with female vocals. The bass is a bit muted and less well controlled, but still stomps the Sophias by comparison. Unfortunately, it has a wooly character to it and seems like it just isn't able to grip the woofer like my Sugden, which is admittedly a tough act to follow in that regard.
Here's hoping the soundstage and bass improve with age. Otherwise, I'll just have to swap amps as the mood strikes me. :-)
