The blips happen at all phases of keypress. They are seemingly random and occur so long as 5-8 are making any kind of sound (attack, sustain, decay).

I measured the 5V pin with my little digital scope and it was seemingly pretty clean as seen in the attached image. Then I tightened the time frame and that revealed some artifacts (see attached video)

I'm not hugely trusting this scope when it comes to correct ranging and proper voltage measurement but the video is probably what is happening in reality. The probes were hard mounted and not shifting. 

So something may be wrong with my +5 V supply. This in not my first PSU problem if so. I had to replace one of the power transistors when I got the OBXa.

I will try bending out those different pins on U164 Monday.