Due to some bad experience trying to get a couple of other SinglePower amps fixed and made 'safe', I decided not to try and get my Extreme updated, but instead get a new and better amplifier. Of course deciding on an expensive amplifier that I can't audition can be a slow and difficult decision. Luckily I had the opportunity to demo the Apex Pinnacle for three weeks, which illuminated my mind and ears to what the best is capable of. As described in my review, I felt I had finally achieved near perfection as regards to headphone sound. But you may also have noticed a sub-current throughout the review of me trying many different tubes in order to get the musical satisfaction I got out of the Extreme and wishfully as I get out of my 45 SET amplifiers. Due to my love of the sound I get from the 45 tube, I just had to try a 45-based headphone amp before deciding if I wanted to spend that much on the Pinnacle. So I ordered a Balancing Act 2a3\45 from Eddie Current. Apparently it currently is the only 2a3\45 Balancing Act, all the others are 300b\PX4 configurations. It came with Sovtek 2a3's, and so I put those in first. They had okay sound, but no music to them. I tried some NOS Globe 45's, but wasn't too impressed either, which made me nervous, as I prefer the NOS Globes to the FJ new stock tubes in my SETs. But I put in a pair of the FJ Mesh 45's. This was the sound I had been looking for! Pure music! I don't think about the sound at all, I just bask in the glorious music. This is what I was hoping for with the Pinnacle. Now that the amp was a keeper, I got a pair of Emmission Labs Mesh 2a3, and a pair of Solid Plate 45's. From all that I've read Emmission Labs Solid Plate 45's have almost universally been agreed upon as the best sounding 45's period. When they arrive I try the 2a3's first, and they are light years ahead of the Sovtek's in both sound and music, but I still prefer the FJ 45's to them. So I put in the solid plate 45's and wow! I see why these are considered the best. Clearly the best music I've heard out of headphones, and it closes matches the music of my speakers - minus the external big sound stage of course. While the 2a3's have a bit better sound, the 45's have a lot better music. As I heard someone else say, the 2a3's make you want to analyze the beautiful music, while the 45's make you want to listen to the beautiful music. While Craig my disagree, from my memory the Pinnacle did have better sound than this version of the Balancing Act (I can't speak about the PX4 version, as I've never heard it), but this amp definitly makes better music to my ears, and the sound is still the second best I've ever heard. The Tung-Sol 'mouse ear' 6sn7 is the best sounding in this amp that I've tried so far. The BA 45 does have a bit less bass than other amps (1/2 dB), and the treble is just a tiny bit softer than other amps (a good thing actually, compared to a 'hard' sounding treble), but since I equalize via the Starplugs 38-band EQ in J River Media Center 15, it is no problem to me. I'm glad I took the risk and tried this amp.