Mac 402 vs 6900

Well that might be something obvious for all expierienced audiophiles but I found it just now...
The power cord delivered with MAC had wrong polarity i.e MA 6900 worked on wrong polarity. I changed it and now everything is much, much better. I had muddy sound no attacks and no detail. Everything was veiled. Now it is a different story. Bass speeded-up and got energy, highs opened-up and veils dropped. I am stunned to hear those effects. Never thought it was possible. I am a happy man now. However I still feel there is a room for improvement in bass erea (even more slam and control). But I don't know maybe I am looking for impessive sounds that are not natural? And would wear me out eventualy

bunkeromantik, How did you ever find the polarity problem. I may be leaning towards the ma6900 again. My listening room is rather small , therefore 200 w/side is all I'll need. You did mention that the bass does not have the wanted impact. Do you think higher wattage is an answer?

I'am not sure how a power cord has wrong polarity. How did you find this out?? Arthur

This is simple but you got to have special "pen" that indicates with neon-light when you touch hot lead. That is how you do it. Looking stright at the amplifier plug with ground lead on top on the right is hot lead. I had it wrong on my power cord.