With reference to the Windows tweaks. All seems to be working well. The wobble was a relatively subtle effect. On the speakers it was hardly noticeable. When I listened on the Koss electrostatic cans though it was more to the fore and prompted me to seek a remedy.
The USB cable (3M not 1.5M btw) listening test was on the cans. The AK70 MkII has a dual DAC setup. Two of the highly regarded Cirrus Logic CS4398 chips. Dual DAC’s are known for having a greater Soundstage, better stereo separation and an overall clearer sound. They also require careful implementation and a linear power supply is recommended. Astell and Kern have implementation well covered and; as it is powered by a battery, power is also sorted. With the cable the overall sound really was much improved. Bass clearer and punchy and mid-range crisper and well balanced. Soundstage though was the biggest improvement. Listening through the Koss cans to 24bit recordings, Fleetwood Mac, Norah Jones, Rebecca Pidgeon, Mahler's 2nd and 5th Symphonies Dubussy Prélude À L’après-midi D’un Faune,,, really do sound better. The analog cable I have from the AK to the A19 amp is of very high spec and even has a built in battery powered cable conditioner. I really have endeavoured to get the very best out of the individual elements of my moderate cost HiFi setup. Regardless what the numbers say. I do understand the paradox of improving the signal to noise ratio of a data stream by running it through a posh cable. It's data! The terms are in themselves are mutually exclusive. It is Impossible!!
"Alice laughed: "There's no use trying," she said; "one can't believe impossible things." "I daresay you haven't had much practice," said the Queen. "When I was younger, I always did it for half an hour a day. Why, sometimes I've believed as many as six impossible things before breakfast."
Sorry to harp on Zybex. I'm with the White Queen on this one. We will not hammer this out I am afraid. But at least we can agree on one thing that we both want the bit perfect.