I know that you said no CD or Tape, but a 1980's old school dual-shaft Concord AM/FM/Cassette head unit would be a nice match or that Nak posted above. Or the McIntosh MX-5000 with Digital Coaxial I/O. My preference would be an old school Sony ES CDX-C910 or CDX-C90 with the digital output if they were still available and reliable. I still use the CDX-C90 in one of my installs and even via its analog RCA outputs it holds its own against any other source I've used.With these items i have. View attachment 333658
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2 sets of NOS never used a/d/s 300i plate speakers (Vintage 1985) and a Mcintosh 420 amp.
I don't want cd or tape, only flac files or higher. I called crutchfield and he sent me 6 decks and not one was available even lol. I don't care the cost it just has to be available.
If you're going for pure SQ and want to play FLAC files exclusively, I would use a high end portable DAP, or an Android tablet or smartphone with the USB Audio Player Pro app, or the Onkyo HF player app on iPhone/iPad with a CCK3 via USB input to the DSP.
I use an iBasso DAP via its analog LO or digital coaxial into my DSPs and it's as good as anything I've heard. Michael Meyers ( @audiophile25 ) was using the Analog out from an iBasso DX-160 DAP in his Subaru Forester SQ system and has done well with it in competition.
If you want modern convenience features, a high end double-DIN or large floating screen head unit would be the way to go. Some of these use a single-DIN chassis and adjustable placement screens in order to fit in older vehicles with a single-DIN opening.
The new Alpine Halo iLX-F509/F511 or iLX-507 units are amazing (7" DD and larger 9" & 11" floating screens), as well as any of the Kenwood eXcelon Reference (XR) DD & floating screen units, or the Sony XAV-9500ES (which is the update to the RSX-GS9 and has a better DAC).
In one of the recent 5 Star Car Stereo livestream YouTube videos, Dean (installer) said that Paul (the shop owner) had just got in a large shipment of many of those hard to find DD and floating screen head units and was willing to ship them. The phone number was in the YouTube video, or look them up in Clearwater, FL.