Terry,
Thanks for the heads-up on that KingKo integrated review. I found the Steve Hoffman thread on it where the reviewing author gives yet more details. Supposedly it's a very good headphone amp too, that can do a great job with the Sennheiser HD600's, which is no easy task. Definitely not an after thought. I believe there were additional windings from the transformer to the headphone out, which would most likely make all of the difference. Possibly making this a tough standalone headphone amp to beat for the price.
Forgive me if you can't post links
http://forums.stevehoffman.tv/threads/kingko-ka-101-experiences.673633/Sounds like a wonderful little amp for very little money. Like you mentioned, supposedly easier to take it even further with inexpensive tube upgrades and adding a dedicated preamp, not that it's required to make it sound good.
I will most likely buy this amp to compare with some others as I continue to build my system around the DI'S.
If it pans out, the DI's with the KingKo amp might be the budget system to beat.
Bill