I'm not even mad I didn't get the adaptor - I heard it wasn't the greatest anyway. Essentially just a network of resistors. Very happy my 300b delivers immense clean power. Regarding the clamping force - I can echo those statements. It does clamp rather authoritatively. I have a large head also, but I don't mind. I'm wondering if the weak bass you are feeling is from wearing glassing and compromising the seal somehow? In any case, the HE6 were never bass cannons. They had detailed, rich, textured bass, but they were never super rumblers. IMO this is the highest quality bass you can get in a headphone - with impact and texture. Anything else would be over the line, just IMO. This is my "perfect headphone bass" headphone. Treble is present. I don't think that will go away. If you find the treble shrill, you might just want less treble in your headphone. The HE6 was never shy about presenting treble as it is in the music - and for some people that's too much. But IMO that also contributes to what makes the HE6/HE6Se special - it doesn't compromise bass and it doesn't compromise treble. Very rare headphones that can walk that line. The HE6 does it the best I have ever heard.