First, I've never really been a believer in break-in, burn-in or whatever you want to call it. I do believe mechanical components have to "settle in" (think speakers) and may show some improvement over time, and I guess that concept would apply to some extent to other electronics in the chain. My background is in music and sound engineering, but haven't done either professionally in more than 20 years. In fact, I was exiting the industry just as digital was entering, so I have almost zero professional experience with modern, digital professional recording equipment. There was a period in the late 80's where I was in the studio either engineering tracks, or playing guitar, 3 - 5 days a week, so though I lack any current technical knowledge, I still have a pretty good ear, and an understanding of proper room setup/recording techniques.
When I first hooked up my 105 via XLRs to my AVM 50v and ran some Analog Direct music via the disc tray, or via the front USB, it sounded pretty good. My first attempts at the Asynchronous USB, using Songbird/iTunes and hi-rez files (FLAC CD rips) were a little disappointing. Pretty harsh and ragged in the upper registers, and generally a "forward" presentation. Since then I have made some subtle changes to my system. Unfortunately, I'm not one to try one thing, test it, report results, then try another... I like to try several things at once, so I can't possibly know at the end of it, what made the most difference! lol
Here are the changes so far:
1. Setup an Analog DSP path in the AVM 50v (just for comparison sake), and adjusted the Analog Input levels to -12dB to remove any signs of input clipping on the AVM 50's analog inputs
2. Changed music servers to Pure Music
3. Since adding Pure Music, I've had a lot more Asynch USB play time (this has been my primary music source over the past few days playing hi-rez HD Tracks downloads, down to 256kbps/44.1khz iTunes downloads - which generally have the worst treble presentation you'll find)
4. I also let a bluray run all night last night... about 10 hours... estimate that I am somewhere in the 50-60 hour mark with the 105
And... this morning the highs, which were slightly ragged sounding out of the box, have mellowed considerably. The sibilance that was there on vocals is almost completely gone, and the overall sound is warmer and more natural. Steve Perry's breathy vocals are now almost smooth as silk, where they were almost unlistenable last week.
Listing to Eric Johnson "Ah Via Musicom" on CD via Analog XLRs right now. This CD has some of the best drum kit audio, especially the snare drum and cymbals. Earlier this week, the cymbals sounded shrill and very forward. Today they are much more relaxed, with less shrill and more air. The snare is snappy, quick, tight and weighty but without the low end harmonics that shouldn't be there anyway... exactly how it should sound. Vocals continue to improve also, with less sibilance.
I will continue to let a bluray play overnight for the next couple of nights to see if the improvement continues. But suffice to say, I'm getting happier everyday with the Analog section of the 105!