Mac sound quality

Tmsorosk- wouldn't necessarily blame Imac. I have used ML
360S for over 5 years with strictly CD. Had the matching
ML Transport (model escapes me). Certain DAC's are optimized for certain type Digital Input. This goes for CD
as well as Computer Audio. Some DAC's sound best with
Firewire Input, others with USB, some with ST-glass Fiber,
still some with AES/EBU. Sound Quality for specific Input
is extremely DAC dependent. Not all Input types designed
with same quality, still the design of DAC determines
optimum compatibility with type of Input. Try the ML 360S,
with its AES/EBU versus Toslink/ST-Glass Optical, utilizing CD. You will hear a huge difference. The ML 360S is a truly Balanced DAC, designed to maximize Balanced Digital AES/EBU Input. Balanced In, Balanced Out is the only way to maximize what ML 360S can do. Even Reviews of 360S claimed that its Toslink, ST-glass Optical was only so-so. Everyone went nuts over its AES/EBU, claiming that it was miles ahead of its other Inputs. I am pretty certain the same applies, regardless of utilizing CD or Computer Audio Input. Try the ML 360S AES/EBU Input for CD, and you will hear what I am talking about. Then decide if you want to keep 360S for Computer Audio, keeping in mind AES/EBU Input to maximize ML 360S for Computer Audio. Are you still using Balanced Audio Output on ML 360S? This will make a huge difference in conjuction with Balanced Digital Input. If not, you are just not hearing everything the ML 360S was designed to provide by a third-at least! It is how this DAC was designed, to be optimized, by Mark Levinson. You can give the 360S what it needs (USB to AES/EBU Converter-or whatever) or concider another DAC.
Compatibility is hyper critical with PC Audio, and design
of DAC determines optimum compatibility with different
type of Input. It is certainly not "one size (type) fits
all with PC Audio.

Thanks Pettyofficer , for your response and the info . I have to agree with you on the balanced aspect as well as ever thing in regard to the Levinson DAC . But I have tried some friends DACs , including a very well regarded USB DAC ,( the mate for my preamp ) with little or no improvement . Have not tried converters yet , would have to buy one to try it . Have not given up yet , but I 'm glad I still have my disc's .
How did you come up with your user name ?

If Toslink, make sure it's GLASS. I think that Audioquest uses plastic (which is vastly more common).

Tmsorosk-Name based on being U.S. Navy Retired.
Many in Computer Audio swear by Firewire, others USB, still
some by Wireless, others by Toslink/ST-glass optical, some
by AES/EBU. You simply can't design a DAC that is optimized
for all of these Inputs, unless you have $20,000.00 to throw away on Inputs you will never use. Manufacturers know
more customers available at lower price. The best that can
be done is to design DAC to be optimized with one or two of
these Inputs. They will throw in other Inputs as nothing more than marketing hype, trying to sell Swiss Army Knife.
Optimum Input is highly dependent on DAC design. There is no "TRUE" Input for all DACs. DAC will be designed to be
optimized with ANY specific Input, but not ALL Inputs. USB
DAC that you tried could only be optimized for Firewire, or
any other type of Input. Not all USB Inputs are of same quality. Not all Firewire Inputs are of same quality either. Neither are all Toslink, ST-glass optical, or even
AES/EBU. Everyone thinks each class is the same quality, after all the connectors in each class look the same.
Manufacturers make profit on Customers presuming that USB
Input on one DAC, will sound just as good as USB Input on
another DAC. The up side of optical connectors, is electrical isolation between Source and DAC. The Downside is having to insert two convertion stages in the signal path. Manufacturer can easily design DAC to maximize advantage of one, and minimize disadvantage of other.
Manufacturer can design DAC to maximize advantage of AES/EBU, like Mark Levinson 360S. Maybe not so much for its
optical input. Not all inputs on all DACs are created equal. Not all DACs are created equal to be maximized with all of their Inputs. Reviewers will usually try all inputs,
and tell you where the sweet spot is. Other Owners of same
Equipment can relate sweet spot Input as well. Just beware
of Pundits who claim that only just one type of Input, is the only ideal Input for all DACs. Unless they Manufactured
the particular DAC, or tried all Inputs with multitude of
other Equipment with various Outputs, how would they know?
I am complete Novice at PC Audio. I would still recommend
the suggestions on this Thread. I would then try a multitude of different DACS with a multitude of different
Inputs. Don't just try one Input type and give up. You could try your friends, or even your local High End Store.
I am sure that they could find you a good combination. They
could even listen to your IMac, and make recommendations.
You could also try the place that you purchased your IMac.
Just make sure that it is someone who is extremely
knowledgable about PC Audio. High End Store is usually best place for knowledge about PC Audio. PC Audio is more
elusive, and alot more complicated mating various components, than other source material. Not to say that other source material is any easier either. PC Audio is
definitely do-able in High End Terms. It just takes more
patience, and time. Sorry, I meant MAC Audio, or however
you classify it (joke! joke!).

Hello:

A couple of things you can do:

I suggest you do not use the Mac's digital audio out. Get a usb to SPDIF converter if you want to continue to use your Levinson DAC. Sterophile has reviewed several of them recently.

Do not rely on itunes alone for playback. Pure Music or Amarra use itunes for book-keeping but substitute their own vastly superior audio playback algorithms.

I'm guessing the biggest issue is using the Mac's digital audio output. If you can, try to get something like an Ayre QB-9 USB DAC on loan, or even something like the new version of the music streamer plus. They both plug directly into the USB ports and you are up and running in 5 minutes. Either of those plus pure music should definitely go head to head with a mid-fi CD player. The Ayre + pure music is guaranteed to kick the CD players keister into the next county.

If you really want to see how good a Mac can sound as a server, you might want to try one of the extraordinarily good Metric Halo or Sonic Studio (the MH re-badged) firewire interfaces. In my humble opinion, one of those with Pure Music or Amarra will not be embarrassed by any digital front end, computer or otherwise at any price.