I went to the shops today to try out the ASG 2, the bass was truly amazing, very low in extension, not unlike the SE846's, what they lack to me are the mids and the trebles. There is a bass port on each driver where one could tune the bass supposedly, but I didn't try adjusting them. I was told the ASG 2.5 are not going to be available until next month or so. They asked me to try out the Astell & Kern AKR03 too and I thought, 12 bands per driver, isn't that a bit over the top? But why not? I got truly blown away, everything was there, every bit of details in the music, from the high trebles down to the vey low sub bass, absolutely nothing was missing! They are the perfect reference IEM! I wanted to get a pair immediately but they were sold out. I then went to my regular shop and somehow they had a pair. So during paying up, I was asking him about his thoughts on the UM Pro series, and he agreed with me that the UM Pro 50 are rubbish, he doesn't even stock them (in fact many shops I've been to don't stock them). When I asked about the other models in the series, he told me the built quality had been lacking since Westone sold their majority stake to a private equity firm, not unlike how when UE was sold to Logitech. He also told me he heard the ASG 2.5, they were supposed to be ASG 2 with different tuning, the bass was being toned down to bring up the highs and the mids, but to him the mids could be tuned up a little bit more. So I guess you have made a wise choice in choosing the ASG 2.5, the bass quality is much better than the UE900s.