Thanks for your very detailed reply. Very nice and impartial comparison between the Okto and your Audio Mirror DAC. No doubt the latter sounds fantastic, though perhaps at least part of the extra cost is due to the extra design work and labor to build a tube DAC.
Troy Crowe is building my new speakers, which except for the back loaded horn will resemble this.
https://josephcrowe.com/products/speaker-system-no-2095 My sealed Altec 416-8B woofers and the same ES450 horn but with B&C DCM50 midrange and Troy's Fostex tweeter/lens combo.
https://www.youtube.com/watch?v=e6QiCzbUhkg&t=496sSystem efficiency will be at least 93dbSPL/w/m. I can't afford a worthy 300B SET amp to drive them, but what I do have is the same preamp that Troy has been using for several years to test drivers and systems.
http://www.dsachsconsulting.com/custom%20line%20stage.html Don Sachs and Lynn Olson had later partnered to design these hugely unaffordable 300B p-p mono blocks.
https://www.audiocircle.com/index.php?topic=185923.0 They will drive Troy's OB speakers that he designed for Don.
https://josephcrowe.com/products/open-baffle-speaker-no-1695And they will drive Lynn's speakers that he and Troy designed; see Lynn’s woofer plans at his thread.
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-767 My sealed Altec 416-8B cabinets are like Lynn’s though my cabinets are 1 cu ft smaller, so my plan is to remove a bit of the cabinets stuffing to gain some LF extension
http://bondedlogic.com/pdf/denim-insulation/UltraTouch-Denim-Spec-Sheet.pdf but also to add my Rythmik F12 subs.
But my first hunch is that my speakers will sound great driven by my First Watt J2
https://www.stereophile.com/content/first-watt-j2-power-amplifier That's because, as shown in JA's measurements, as long as the speakers' system impedance always remains far above 4 ohms (definitely my speakers) any distortion will be mostly 2nd harmonic.
Of course, there's long been lots of evidence that what many tube hardware owners tend to love is the 2nd harmonic distortion produced by those amps, so long as 3rd harmonic remains very low. However, if I'm somehow not wowed with the J2's sound I will put the Sachs preamp between it and the solid-state DAC (which??). Of course, if anything the preamp will add more 2nd harmonic, which may end up sounding either better, worse or about the same. What’s weird about the J2 is that while 2nd harmonic is dominant most users say that amp does not sound like tubes.
https://forum.audiogon.com/discussions/first-watt-j2-speaker-pairinghttps://forums.stevehoffman.tv/threads/j2-first-watts-stereo-power-amplifier.1159482/https://forums.stevehoffman.tv/threads/the-firstwatt-j2-is-the-perfect-amp.891992/Hoping to report happy sounds with the J2, which I hope will outweigh the bad of its power draw and heat emissions.
But if I'm still not pleased then the last trick in my bag is the Sachs preamp feeding my First Watt F4.
https://www.6moons.com/audioreviews/firstwatt6/f4.html Most of that amp’s distortion is apparently 3rd harmonic, but many have mixed feelings about its sound. But most tend to agree that when two F4s are configured as mono blocks sound quality zooms up.
https://www.diyaudio.com/community/threads/the-f4-is-a-jewel-and-seems-underestimated.336597/ I do have two F4s but the power draw and heat emissions of these Class A amps preclude that option, plus the combined wpc would be total overkill for my speakers. That’s a shame because the additional of the Sachs preamp (which the F4s need anyway because that crazy amp has no voltage gain)
would no doubt make those mono blocks sound even better.
Looking forward to some exciting sounds.
