The Z5 has aluminum coated driver and sub bass is the same as the full sized Z7. The purpose of that on a 70mm driver was clear though. It had mixed results. On a 16mm driver? Not sure why they did that. I took the A2 as the Z5 was bass dominant and it couldnt be dialed down and it was peaking around 70+Hz and was lacking clarity ASG 2.5 hits very hard,can be dialed back, has a bass slope with a peak closer to 55/60Hz and is coming into the picture already elevated at 30Hz....not climbing like the Z5 or 2.0 ASG. This is easy to confirm with the test track we use on the over ear tests "On my Level" by Wiz and Too Short which lives in the 30Hz area. The 300Hz is dipped a tad or overwhelmed by the Sub-bass. These cost 800bucks in Japan so I was pissed but I lifted the 250Hz slider a touch and male deep vocals were back in the game and I stayed up way too late enjoying going from sub bass test tracks to guitar plucking to Boston's Foreplay and being blown away.