I was looking for someone in the DFW area.  I'm glad I found this thread.  I highly recommend Gary Dodd.  He is a true pro at this.  I had what I thought was amp and/or pre-amp issues, called Gary up, and brought my stuff over.  Gary did his thing quickly and thoroughly and found the central issue (was a bad cable in the chain somewhere in my setup).  I went home, plugged in the old set of cables, and I'm back in business.  I won't hesitate to use his services again!
Thanks for the recommendation, Art!  BTW, I forgot to tell Gary hi for you.  Between catching my breath while carrying 90+ lbs of amp and 60 lbs of pre-amp back and forth like a strong-man competition (for weaklings), and holding my breath in hope that $8K of gears were not damaged, I had forgotten to let Gary know 
