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At what point is an external D/A converter warranted or beneficial

Over the years and after multiple "upgrades" I've become disillusioned with digital audio reproduction. As my systems improved in quality/resolution, the digital audio quality has equally deteriorated to where most listening is now done in analog. This makes my CD collection of in excess of 1000 titles pretty much useless. My digital D/A conversion knowledge is pretty much limited to whatever is done by the internal D/A converter of the equipment. That being a Lexicon MC12B processor and Oppo BDP103. As my choices of ICs went from basics to high quality resolution improved with a marked decline in digital SQ. I'm at a point where any Redbook CD presents a harsh, edgy, shrilly, bright, name it what you want, upper frequency. Changing ICs back to basic cables attenuates this along with resolution of the music played. You might say I'm at a loss. Do I live with less resolution or the digital limitations. I do not have this issue playing analog media. Would an external D/A converter be beneficial or a waste of money? 
Systems are: B&W 803D2 and surrounds,  Lexicon MC12B, Oppo BDP 103, AQ Columbia ICs XLR & RCA,  AQ Digital ICs,  Tara Labs speaker cables,  Rogue Pharaoh, VPI Prime . Analog front end shares the L/R front speaker and input from the Oppo. 
Is there such a thing as an external D/A converter for a H/T setup as the Lexicon processor is the oldest piece in the chain with most likely the weakest D/A converter. But how would that connect to avoid the internal processing.
Any suggestions or recommendations?

128x128gillatgh
gillatgh's avatar
gillatgh OP
381 posts
 
@noble100, some things I've tried so far trying to isolate the issue. 
1. At Oppo 103 Swapped digital IC from optical AQ to coaxial AQ Haweye which resulted in an increase of high frequency brightness using HT Lexicon. No change noticed using the Rogue.
Note: connection to Rogue is via analog out of Oppo where the Oppo internal DAC is doing the conversion. There is some hf brightness but not as pronounced. I think the Rogues tube section is attenuating the hf signal.
Also noted that this hf anomaly is isolated to digital only not an issue during analog playback. Also streaming from Spotify or Pandora directly from Smart TV seems to be no issue. However when using the Pandora app in the Oppo the brightness returns. I have yet to get to trying your suggestion as that will take more effort and time. 
Ps. The Lexicon processor has never exhibited this phenomenon prior to the Oppo introduction. 
gillatgh's avatar
gillatgh OP
381 posts
 
A point I forgot to mention, playing back a DVD thru the Oppo (concert, both BR and standard) exhibit none of the hf issues encountered when playing Redbook CDs. My issue seems to be limited to CD playback. Playing DTS cds also do not exhibit any hf issues.
Very strange!
noble100's avatar
noble100
2,419 posts
 
Hello gillatgh,

     Yes, it is a bit strange but it's not brain surgery, right? 
     I no longer believe the Lexicon MC12B is the source of your issue.  It seems, in your current setup, you only use its internal dac chips for ht processing and you use the 103 for cd playback connected directly to the Rogue.

    However, I'd still suggest removing it because it's unnecessary and using the 103 for surround decoding, and connecting its outputs directly to your 5 ch amp, will likely be a significant improvement for ht sound quality and it'll streamline your system to just the necessary gear.
     Once you get the time to reconfigure and setup the 103 as the 5.1 processor, there are some other features on the 103 you can explore. 
     Things like the audio processing setup screens where you set the size ('small' for sub assistance or 'large' for no sub assistance) and relative volume of each of the 5.1 channels, the cutoff frequency for bass sent to your sub and how you want 2ch stereo cds to be processed and outputted.  You could get a head-start on this by reading these sections in your 103 manual. 
     I'll monitor this thread and await updates.

Tim
      
 
gillatgh's avatar
gillatgh OP
381 posts
 
@ noble100 and all that contributed,

Tim, in two words, YOU ROCK!!! 
Reconfigured my system as you recommended, also read the Oppo manual, with a slight change. Instead of using the Oppo as the preamp I kept the Lexicon in the loop. Configured as follows, removed the digital connection completely and connected the Oppo to Lexicon via analog out to 5.1 analog in connection on Lexicon and set Lexicon setting input to analog bypass so the Lexicon DAC is bypassed and processing is done by the Oppo. Only loss to this configuration is inability to convert 2Ch into Lexicon proprietary surround modes. Quite ok with that as I do have the ability to just change a setting if I want to use them.
Now for the result.........WOW no more harshness, brightness etc at high frequencies, open airy superb. Much more defined and clear. Extra bonus my SACD and DVD A disks now also play. I'm thrilled and really a happy listener.
Redbook CD'S are sounding great like never before. I may have to change my mind about digital. Analog still has what I'll just call some ambience that digital is missing but in the big picture the convenience of digital is a worthy contender.

Thanks to all who took time to make suggestions. All of you are superb music affectionados but Tim, noble100, absolutely had the best and most cost-effective solution. Great ideas and info.
My problem is solved. Again thanks to all.
noble100's avatar
noble100
2,419 posts
 
Hello gillatgh,

     No problem I enjoy helping the humans.

     I'm glad you like your new setup.  When you have the time, don't forget to go to the Setup Menu and configure your 5.1 system for optimum performance.  

     Go to Setup/Audio Processing/Speaker Configuration.  Use your remote to scroll to the Test Tone box and then use the l/r arrows to select each of the 5 spkrs and the sub.  For each spkr you set the Size (Large for no sub assistance on the spkr Small for sub assistance) Distance (approximate feet the spkr is from your listening seat) Trim (spkr volume-you want all the speaker volumes about the same relative volume at your listening seat).  When completed, you can use the l/r arrows on the remote to sequentially play the test tone through each speaker and verify all channels have the same relative volume when at your listening seat, making small adjustments to Trim and/or Distance on each speaker til the test tone sounds equal from all the spkrs.

     You can also go to the Crossover section and set the frequency at or below which bass frequencies are sent to your sub.

     Probably best just to read the Oppo manual on this stuff, too.

     PM me if you need more help.

Enjoy,
 Tim
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