A fit of Audiophilia

I am an 81 year old retired software engineer who still dabbles in that activity and am stuck trying to find a minor bug - which has nothing to do with the post except for being the reason for a glass of wine and the striking of Audiophilia.

I started to wonder about different file formats, external clocks etc.

A telling track for my critical listening is the "Bless the lord" from the Sveshnikov 1965 recording of the  Rachmaninoff All Night Vigil.  This has deep Russian octavist voices, a wonderful choir, the intense emotional voice of Klara Korkan and was recorded, I believe, in a basilica.  

In addition to the LP (which wins) I have a DSD128 and PCM 24/192 recordings.  Level matching the digital sources was tricky but playing the DSD at +5.5 dB was as close as I could come. (DSDs are usually about -6dB to avoid stability issues near 0dBfs).

The DAC is the Esoteric K-01XDSE which is a ΔΣ device and so operates internally in DSD 512.  I was listening with 4x upsampling, PCM filtering M1, and DSD filtering off.

The  PCM won, its slightly higher resolution yielded a slight increase in (surprise) resolution.

Conclusion unless something was mastered at better then DSD 128 if PCM 24/192 is available, use the PCM.

I then tried the experiment with and without the external SRS FS 725 clock,10 MHz, sine wave, 50 Ohm.

The K-01xdse has a very high quality OCXO clock but spatiality, these sense of the singers as 3D people, was noticeably improved by the external clock.  The FRS 725 uses the same physics package as Esoteric used to use in their $20k clock (they now use an OCXO clock at a slightly lower price). Conclusion, an external clock may well be worth it.

I do not have a spare $16k to compare the new Esoteric G-01XD with the FRS 725.  But the Stanford Research Systems unit is a bargain.

My clock cable is an entry level priced component usually used for uhf broadcast application, so now I am wondering if I can get even better SQ with an "Audiophile" clock cable, I am thinking of the Shunyata Theta or the Mutec PSC 50.  There are some insanely prices Shunyata and Esoteric products but ...

After all that the 60 year old Melodiya disk has a richer, deeper timbre and greater spatiality - but perhaps that is the effect of the Koetsu RSP/Sutherland Dos Locos front end.