Chilledspode

Hi George, Nicely done :-) I suppose that is possible. I have been operating under the assumption that since the usb outputs function perfectly fine for everything other than for hifi audio to my dac that I am facing something more subtle than a defective machine. I am coming to believe that wwmfan has it right in his speculation that El Capitan is a big part of my new issue. This is great site and I appreciate the time and effort people have given to help me understand what might be happening Thank you all Mark

wwmfan - thanks for the information, I am a total noob at computer audio stuff. El Capitan - I am running a simple iTunes environment using home sharing with 3 macs, 4 ipads and home sharing gets clunky between different osx editions. Having said that, based on your initial reply I did some internet searches for ELC/usb and clearly this newest OS has a history of usb related issues - I didn't do my homework, I trusted Apple and I got what I deserved. :-) Thanks for vote of confidence on usb to the M51 as my early reading suggested this was a good approach. I can see spending a lot of money on going the aes/ebu + convertor route but am intrigued by the corning cable which appears to be a usb > optical>usb cable - will the M51 interpret that as a usb source? I ask because I prefer the 192 oversampled sound of usb sources to the 44.1 sampled digital coax source material and don't want to lose the oversampling of usb option. Cheers Mark

Tone deaf - fair comment on shortening the usb run to see what happens - just not sure how I am going to actually pull that off ... :-) Neither the mini nor the M51 are easily moved to shorten the distance. Let me ponder that for a bit Cheers

Ok - did a bit of quick research and long aes/ebu cables are not going to be an issue. I live in a small remote town in northern Canada and am going to have to order the aes/ebu canle in - any recommended suppliers? Cheers Mark nb: I will try to revert back to Yosemite and see what happens...

wwmfan - I appreciate the USB was a bad call but it got me started in computer audio and with the original i7 mac w/Yosemite, worked quite well - now not so much :-) I have always counted on improving my cabling at some point and now the need is upon me. Thank you for the link - I don't know much about AES/EBU cable limitations - could I run a short usb to the converter and a 25-30ft AES/EBU to the M51? If not what would you consider to be a good approach to reaching 30ft from the mac to the M51? Cheers Mark

It is a 'boosted/powered' usb cable built for long runs and it was working fine with the previous mac mini. Based on this, I do not think the problem is the usb cable. I am using something similar to this one: USB Extension Cable Active Extension for repeating USB cables and signals Cheers

I thought about that but since the issue showed up when I changed out the mac mini and nothing else physically, I figured the cables should be ok. Upon reflection, I upgraded to ElCaptitan when I changed machines so I changed two things at once - I know better, duh. Do you have a recommendation for long usb cables (30ft or so) ? Cheers Mark

I did some searches here but couldn't seem to hone in on my particular issue. I had a 2013 mac mini i7 256GB SSD 8Gb ram using iTunes feeding my NAD M51 via usb and everything was fine - ElCapitan and current version of Itunes. I needed more access to the hot rod mini (it was the main home/family computer) so I bought an older 2009 mac mini Core2Duo and put a 256Gb SSD in it and it has 8Gb ram and swapped out the i7 mini for the older 2009 model. That change to the older mini produced continuous pops/clicks/etc using usb audio out - it was unlistenable. Tried putting a AC powered usb 2 hub between the mini and and the NAD M51 and it made some improvement but not enough to be acceptable. I have tried all the usb ports on the mini and they all produce terrible outputs. Tried bringing my 2012 MBAir into the system to provide the usb audio source and discovered the left side usb port is awful but the right side was pretty good and only produces an occasional pop/snap and I could live with this, but I want to fix the issue with the mini, but I don't understand what the real problem is and how I should go about fixing it. Do I need a 'magic box' to cleanup the usb signal? Should I be going from usb to some other format? etc... If this issue has been discussed, could someone please point me to where and I'll gladly read up on it - thank you for your time. Mark

I also felt the M50 was a bit of overkill so I went looking for an Ethernet port on something else - the NAD C446 Media Tuner looks like it might provide the same network connectivity at about 1/3 the cost. More research required... :-) i have put the question to NAD directly and I'll provide their response here, once I have it. Cheers phat. mark

I do have a MBAir lying around not doing much but I want to leave that option for the moment. I am fixed on something coming out of what Doc said regarding network vs usb sources... I have considered replacing my relatively poor cd audio player with NAD's M50 which has an ethernet connection - I am curious as to the implications of this as it occurs to me that this might allow for a direct/continuous access by the stereo system to the 'NETWORK' and therefore my media library on the direct attached external raid drives. It this line of thinking reasonable or fatally flawed? Thank you again, for your time. Mark

audiodoc : Can I ask for clarification, without wiring schematics I am struggling to keep things straight in my head - does a NETWORK need to include at least one computer or in my case can it consist of just a wireless router + Internet connection and possibly a future NAS. Cheers Mark

Thanks again for coming to my aid. You have recalled correctly, my situation. I need to think this through, but the Existing setup with iTunes sharing on allows the kids to access iTunes media wirelessly with their laptops, iPads, iPods, etc. The real issue is my wife and I share the mini as a workstation and this creates the hifi audio source problem and as far as I can understand things this can't be resolved without a second machine that would become the media server/audio source for the stereo. Do I now have this correct? Cheers Mark

Thought I would try to add to the knowledge base on this thread. I tried a number of things and none of them resulted in satisfactory improvements to my issue. I subsequently contacted Apple and put the questions to them, to which they replied: 1) you can not maintain usb audio out while changing users under osx 2) you can maintain Apple TV connection for audio while switching users but with that you get the limitations that come with routing audio thro apple tv 3) osx server will not overcome this issue according to apple server group 4) apple doesn't think a nas will solve the issue either but of course couldn't comment knowledgeably about 3rd party hardware (like synology) 5) the only way for me to get my system to work as I want it to is to add a second machine to be the media server accessing the usb raid 1 hosted media attached to the current mini. i would be interested to know if people agree that a nas (synology or otherwise) would not allow uninterrupted access to itunes media through a direct usb connection to my DAC. Cheers and thank you all for helping a CA noob work through this stuff. Mark

Yup, my squirrel brain still thinks I haven't got this totally figured yet. Doc brought me along way and I was going to do more research over Christmas. I have done the Apple TV thing and while serviceable for audio, there is no going back after listening to full potential of usb to the M51. I don't think I can hold together a headless mac mini from an intellectual level - I seem to be struggling hard enough with a single machine. :-) Can I ask you to elaborate on your thoughts regarding how Audirvana+ might factor into helping my situation. Thank you Mark

Obviously a subtle but significant difference - makes sense now. Doc, thank you very much for the kindness and enlightenment. Merry Christmas to you and yours Mark