I have been using a modified SI T-Amp for about 6 months. I have been very happy with it running my K1000s. Based upon this experience and with my enjoyment of DIY I decided to try another Tripath kit which would give me a bit more power and allow me to upgrade parts more easily, especially the input capacitors which on the SI are too small a value and very hard to replace without trashing the board.
I chose a kit from Audiodigit which is sold through Autocostruire in Italy. http://www.autocostruire.it
. A similar kit is available from www.diyparadise.com
and gets very good marks on the Class D forum at www.diyadio.com
The short version is that this thing is remarkable: tons of detail, a rich midrange, and way more quality bass than I thought that the K1000s could produce. The only changes I have made to the circuit so far were to replace the input caps with some polypropylenes that I had on hand and to replace the on-board power supply caps with some Blackgates. I have the amp running on a sealed lead acid battery right now but I have an SMPS power supply coming to try out.
Hanging out in the Class D forum has also gotten me interested in the Hypex UCD amp modules which can be obtained through DIYcable.com. The modules produce well over 100 watts of very refined and quiet Class D power. Supposedly they are even better sounding than the Tripath amps and do not have the problem of rising high end response as impedance rises. This rising high end is why it is a good idea to put a ~5 ohm-5 watt resistor accross each output to give the amp a more "normal" load. These UCD amps also allow you to wire the outputs into a normal headphone jack because they do not float their output ground above zero like the Tripath amps.
The two T-Amp stereo kits are each under a hundred dollars. The UCD kits start at $80 for a single channel. You will still need power supplies, case, connectors etc.
If you are inclined toward DIY things are looking pretty great for K1000s. I will post again after I get the Hypex amp built