I just got the 7HZ Timeless AE last week! While it is fairly power-hungry compared to most other relatively cheap IEMs I've tried, I've been able to run it right off of my phone using the Apple Dongle with no problem (volume around 70-80%). When I paired the Timeless with a variety of delta-sigma sources, the Apple Dongle, my M1 MacBook Air, DD HiFi TC44C, and Ferrum Erco, I really didn't find that much of a difference in bass response.

At the end of the day, you should do what you enjoy most. If you want the BlueTooth capabilities of the BTR7, go for it! But if you're just going to use it as a phone dongle, you may want to reconsider.