Do you happen to know which effect mode was enabled on the AT-PHA50BT?   From the manual it looks like the AT-PHA50BT supports the following effects: Flat (OFF) Acoustic Vocal Boost Bass Boost Virtual Surround

There is also the new Audio Technica AT-PHA50BT Portable Bluetooth DAC/AMP, for about 13,000 JPY ($110).   I'm really curious if anyone has experience with this, especially paired with re400 or similar.

This is about half the price of the E5, and looks very nice. I wonder how it sounds with re400?   https://www.audio-technica.co.jp/atj/show_model.php?modelId=2661   In english...