I've now had the TD-11 for over two months and am very pleased. I use the tube output on my Audioengine A2s and the result is deeply impressive now that I've tamed the previously massive bass resonances in the A2s, but that output won't drive my 32-ohm Grados worth a darn. For that, I need either the headphone jack, or I connect the Y-adapter to the solid state outputs and hook the phones up there. Sometimes I hear better headphone sound from the SS outs than the headphone jack, sometimes not so much. I can't decide if it's a volume difference or a quality difference.
I've noticed one weird thing with the TD-11, and I can't tell if it's my computer or the DAC. If I leave my computer on but shut off the DAC at night, then power the DAC up again the next morning, I get nothing but static from the USB connection at first. Over a period of about ten minutes, the static fades and the music starts coming through. There's no such problem from the SPDIF connection. Go figure.
The TD-11 serves my desktop system almost exclusively. I originally bought it thinking I would run the SPDIF out from my vintage JVC XLZ 1050TN CD player into the TD-11, and run than directly into my Acurus A250 amp so I would have an upgraded front end and a tube somewhere in the chain to benefit my Martin Logan SL3 speakers. The TD-11 was to replace my Acurus L10 preamp. Well, I learned that as good as the TD-11 is, my 20-year-old electronics are better than I thought. The best configuration is to put the TD-11 between the cdp and the preamp, and that does offer a subtle improvement from the mids on up. The truth is that I rarely get to listen to my big stereo any more. That's why I love desktop audio, now.
My only comparison is with my Audioengine D1 DAC, which I use now when I travel. The TD-11 is smoother, with better transparency and mids and highs. To its credit, the D1 does have sledgehammer bass, even when dropped into my big rig in my listening room and driving the amp directly, but it's bright at higher volumes and gets rather congested with transients in that set-up. So, yes, the TD-11 is a better DAC and headphone amp than the D1, and it should be at twice the price. Neither one is shamed and I'm fortunate to own both.