cj,
Those 5998A's are pretty much repackaged 6as7s (I have a pair), we'll need to find out if you've got some older 5998s in the tube compliment included with the amp and if not find a way to get you a pair at some point. I'm not saying the A version is bad, but in my listening experience no where near as good as the real old 5998s.
And I see you got your cable back.