I have the Fosgate. I like it a lot with my Lyra Delos. I've done extensive tube rolling with Telefunken 12AT7s, 12AX7s, Amperex 7308s, RCA 12AT7s, Mullard 6922s, Brimar 6X4. After all of that, I think the stock tubes sound the best because whatever minimal differences there were with the NOS ones, they seemed to exaggerate an already fine balance of tonality. The Fosgate really only has one tube that makes a significant change in sound and that is the V3 position. It's stock with a 12AX7, but comes supplied with an additional 12AT7. I prefer the 12AT7. For some reason, the 12AX7 produces way too much bass from maybe 60Hz down (?) (I use subwoofers; it might not be as noticeable without). When comparing a CD with the same mastering of the same album on vinyl, the bass is crazy boosted - like the bass knob is turned all the way up, I'm not kidding. Some titles are worse than others (kick drum on ZZ Top Tres Hombres on Rhino comes to mind). But, strangely enough, using the stock 12AX7 with the KAB Rumble Filter, the exaggerated bass sounds perfectly balanced and sounds amazing. Without the rumble filter, and using the optional 12AT7, the bass sound is balanced, there is reduced glare in the high end (compared to the equivalent CD), sounds somewhat "creamy," but also sounds big and rich. It's not dull, but it's easy on your ears at a high volume compared to CDs. I wouldn't mind using the Fosgate with the Rumble Filter, but the filter does take away the tube bloom in the mids and some of the sweetness in the highs that I like, and I'm not into the fact that it sums all the frequencies from 140Hz down into mono. I've got plenty of LPs with stereo bass and I notice it doing needle drops. I prefer the mids and highs with the 12AX7, but the best overall sound for my system is using the 12AT7. I have noticed that the Fosgate tends to show more contrast between a good recording and a bad one. If it's a boring mix, you'll know it, and if the EQ is too boosted, you'll notice that too. I didn't notice this with my cheaper SS preamps. It's a killer sounding unit and is much more enjoyable to listen to than the other 2 solid state phono stages I've owned. This is my first piece of tube gear and it does sound different from solid state. Some times I like the bloom, sometimes not. I usually don't like it as much on modern recordings that use loud-mastered digital sources. It's still good, but I think it needs some of that SS definition to cut though a smashed master. However, if the record has a decent amount of dynamics, I prefer the sound of tubes. It sounds not only more life-like, but sounds bigger and deeper, at least with the Fosgate.
