Hello all, after setting tape head on one tape (pre recorded)and its crystal clear on both speakers, you take out the tape put in another and it requires re-adjusting and some boxes you seem to have great difficulty getting a happy medium, is there an easy solution to this as all these tapes are pre recorded by music manufacturer,and can give brain damage.cheers, paul.

The answer lies within your question...

Its all about happy mediums.

Most better quality pre-recorded cassettes should sound about the same, but without knowing what tapes have been used for pre-recorded albums it'll be hard to know which to use as the standard.

Azimuth adj is like a factory set-up, once adjusted you must stop. Don't play with this, it ins't an user control and you would damage where the screw thread, since there's a spring betewn head and chasis.
Of course, adjusting it would makes you recorded program sound a little clear, but you have the tone control to get the same feeling with all recorded programs, while head azimuth it's adjusted to an average position. It's imposible that your BBX match always the azimuth of the machine that made the recording.
When a BBX have several problems to adjust and the point seems to change even on the same tape, you need to check the head. That happens when the head face isn't enough smoonth (worm-out head).