I think I am done, for a while, besides the ZMF.
I think like you I'm probably done with any more audio changes this year. I was always super interested in the Fiio K15 and K13 R2R releases and whether they could replace my Fiio K7. But I think I'm coming to the conclusion that either are not just quite right, or maybe a bit wasted on me.
K13 R2R appears to use the same R2R as the K11 R2R. So there's this 'distortion' to deal with and whether I want this in my main DAC/AMP. Then there's the reliance on Fiio's volume controls (I didn't like this on the original K11) and a form factor that doesn't quite work for me as smaller units.
The Fiio K15 seems to have not really created much buzz. I can only assume some of this is Youtubers who think it's just a cut-down K17 and that's reason it's not been reviewed as much. Again form factor doesn't work as well. Dependant on software again and I'm not sure how much of an audio improvement this will be on the Fiio K7. There's also a few bugs raised on Head-Fi which don't seem to have had Fiio's attention yet. The one advantage the Fiio K15 would bring is more i/o and that could mean I remove one, or two other units from the desk which is a positive.
And for headphone use I tend to prefer the iFi stack, or my Gremlin, so that again makes me question what is it I'm looking to upgrade the K7 for. At some point in the future I'll look OTL Tube amps again, but not today. Headphone wise I went a bit silly with five HD 6x0's over the last 18-months, but for music I found my headphone. At least for now. And for gaming I'm well covered with the PC38X and TYGR.
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On another note I've been using Musicbee and I have to say I actually really like it. Over the years I've used loads of music players on Windows, Mac OS and Linux, but always had a preference for Foobar 2000. And whilst I'm not sure this replaces Foobar, there are some things about Musicbee I prefer. The ease to switch between ASIO/WASAPI playback, easier configuration of layout options, greater theme variety and it's a better looking player overall. Overall it's easily up there.
I only mention here in this thread, as it came up as a recommendation from mrk.