Once I confirmed a happy connection—Qobuz Sublime launched as usual—I decided to start listening over HifiMan Susvara with Dekoni pads. Partners in crime were the usual Sonnet Pasithea DAC and Cen.Grand Silver Fox headfi amp. Going to the 'my purchases' window in Qobuz, I had quick access to albums also downloaded to my SSD drive. I could readily compare the same files off the cloud and local library to see whether my gap had narrowed or closed. Comparing with/out iSO-CAT7 obviously required a quickie rewire.

And wouldn't you know it, the three versions of Audirvana, Qobuz 'direct' and Qobuz via iSO-CAT7 did sound different. With ultra-high res from premium headfi eliminating room bloom, it wasn't difficult to parse these flavor distinctions. That qualifier was key. General room reverb and modal resonances are grosser more substantial factors. They obscure or at the very least diminish this type effect which transducers within centimeters of our ear can lay bare. With my speaker system nicely sorted considering constraints of funds and renting, I could still tap into remnants of these differences. Just so it was far easier to hear what caused them over the planar headphones.

They played out like mild echoes of PCM/DSD observations which I'd made well before with .dff files and my upstairs Cen.Grand DSDAC 1.0 Deluxe which also resamples all PCM to 128, 256, 512 or 1'024 DSD.

With my hardware and ears, PCM sounds more resolved particularly on recorded ambiance and PRaT, has superior micro detail and greater treble light. It also sounds more articulate on transients and more damped on decays. DSD sounds softer, spatially more billowy, bloomy and fuzzy so with less actual recovery of recorded ambience, generally warmer and slightly elongated on decays. I decidedly do not find DSD64/128 competitive with quality PCM on sheer resolution or treble insight. I hear a slightly cloying gilded patina. Meanwhile upsampling DSD64⇒256 nearly repairs what versus PCM is plainly truncated treble. DSD512 virtually restores it but still remains softer overall. In my book DSD1'024 over 512 is mostly bragging rights for a big fat number. In the context of today's discussion, the Audirvana stream of local files represented top-quality PCM flavor. Qobuz 'direct' stood in for DSD64, at best DSD128. Qobuz with the iSO-CAT7 looped in became DSD256/512.

The SOtM lozenge clearly played at minor influencer. It clarified and better articulated cloud playback yet didn't rewrite the fundamental flavor offset against playing back local files through the dedicated music OS that is Audirvana Origin. To add cloud-file routing to Audirvana requires their Studio license which I don't possess. So I can't determine how much if any of the gestalt offset was due to Origin massaging local but not cloud files. Having described my three different paths as being reminiscent of PCM, low-rate DSD and high-rate DSD, it's vital to now stress that even a rather fine speaker system like ours still made them rather closer neighbors than extreme headfi. In truth I'd not bother with this extra stuff on the iMac's derrière if I didn't also do quite advanced headfi. With Susvara however I appreciated the level change. There I shall call it relevant and desirable. With it cloud streaming still wasn't identical in gestalt to playback of local files. But it now registered as more of a sideways move into a slightly different feel than being a step down into lower fidelity. After I'd set my expectations low going in, this in truth delivered more than anticipated. I could hear and appreciate what the iSO-CAT7 does once I presented it with appropriately high resolving power. Time to set up my second test bed: DSP-corrected sealed active nearfield speakers from DMAX fronted by an iFi iDSD Signature Pro DAC. That itself is fronted by a Singxer SU-2 USB bridge which upstream sees an iFi iPurifier and Mercury 3.0 USB cable that seats in an HP Z230 Win10/64 work station as my office computer. That same work station gets its cloud files via CAT8a cabling from our fiber-optic router/modem which itself hardwires to a node on the mast outside my office. Phew.