4 or 8 ohm ?

You may find the 8 ohm tap to yield better hi-frequency reproduction.If it doesn't control the bass,use the 4 ohm tap.As I understand most transformer output set-ups,the actual "matching" is lower than that stated {IE;8 ohm is closer to 6 ohms}.

A 6 ohm rating is it's average. We don't know what it's extremes are to come up with that average. It may have some serious dips that could be hard on your amp using the 8 ohm. Do what Aball says and try both. One will likely sound better to you. If you don't hear much of a difference, then use the 4 ohm. Good Luck

Thks, I will try and let my ears judge...I was just worried about something happening to my amp.

Rgds,