View Full Version : Weird 7520 DAC behavior - looking for explanation

04-12-2013, 07:11
I am using latest A+ on my Macbook with 10.7.5 Mac OSX connected over optical out to my Beresfrod Caiman Gatorized DAC 7520. This DAC is connected over the RCA's to my Marantz PM6004. Additionally, my Marantz CD5004 is connected over high quality, digital RCA coaxial cable to the same DAC, giving me the option to have the same sound signature and use the CD player as transport device.

What I have recently noticed using my headphones connected to the DAC directly, while listening to the CD, lots of distortions were audible in the sound, like clippings. I thought at the beginning that there was something wrong with the CD mastering, but when I switched on the amplifier, all of these disappeared. While still listening over the cans, I switched the amplifier off again, and all the distortions came back, clippings like, ticking etc?! My speakers were muted in all cases.

Cannot explain it to myself, what is the reason? It seems that powering on the amp change something in the DAC when the signal is transported over that digital coax cable to it. When I listen to the same CD ripped to my Macbook over the optical cable connected to the DAC over the same cans, it doesn't matter if the amp is on or off and everything works fine?!
Anything related to the impedance or something?

Second weird behavior is related to the A+ and how the CD sound over the same DAC. I don't use oversampling for the redbook material and in A+ preferences I had custom pane used to oversample everything, except the redbook to the maximum of my DAC capabilities - 24bits/96kHz. When I change the oversampling preferences under the A+ to global NONE choice, means no oversampling at all, boy, everything opened up and the sound changed was dramatic! More open, HUGE soundstage, everything changed to the better sound - not only redbook files, but also 88.2kHz, 48kHz etc. Even my DAC does not natively support 88.2kHz or 192kHz.
Any explanation to that in your opinion? If DAC does not support the 192kHz or 88.2kHz (these are even greyed out in the Mac OSX midi setup) and I have oversampling set to NONE, what is doing the over/down-sampling in that case?

Still scratching my head, what the hell is happening there?