TEST: Older R2R Tube DAC vs Newer Delta-Sigma Solid-State DAC

After reading a lot lately about the resurgence of R2R multi-bit DACs, and other strong opinions about one DAC vs another, I decided to do a little experiment, and do a direct AB comparison between two DACs:

1) Wyred4Sound DAC1LE (with Femto clock and other upgrades): Purchased new 3-4 years ago.  MSRP was around $1,300. Uses ESS Sabre 9018 delta-sigma 1-bit DAC chip. Solid state output.

2) Lector Digicode 2.24 (recently serviced and replaced tubes with new Gold Lions). Purchased used (came out around 2002). MSRP was >$5k. Uses 4 Burr Brown PCM1704 multi-bit R2R DAC chips in fully balanced configuration Tubed output.

Both DACs were connected to a Sonos Connect unit feeding a BAT VK-5i preamp, and VK-55SE amp.  I warmed up system for an hour or two, then with each song I played, switched between the two.  I adjusted the volume to match levels.

Result?  Very, very close.  The older Lector unit sounded like it had just a tad more 'air' and a bit more soundstage depth, but I had to listen very closely, and the difference wasn't always that apparent.  There were no other obvious differences that I could detect.

What does this mean?  Well, I don't purport to have golden ears, and have not had my hearing checked, but I have had some 'training' (I was a recording engineer for a while, and was an amateur musician for many years).  I do believe that there are some *very small* differences that I just can't discern very easily, and have to listen quite closely to discern the ones I *think* I can hear!  I do believe that quite a bit of the differences we hear are because we *want* to hear them (not criticizing for this BTW; just my belief).  I was surprised however given the differences in age, topology, architecture, etc. between the two DACs, that I couldn't hear a bigger difference.

By the way, I do understand that some don't believe in the idea of direct AB testing.

What do you guys think?