I did this a few years back. I couldn’t find them all in stores either but I tried what I could. Even stopped at stores in other towns when I was out of town for the day. That eliminated some. Read a lot of reviews, watched a lot of videos online. Some useful, some not due to subpar production. Came across a video shooting out the mesa subway vs the Aguilar tonehammer. By that time for me those were the two main contenders. Funny thing is the reviewer in the video preferred the Aguilar but I preferred how he sounded with the mesa. So I think a lot of it is personal preference. There is no best class d amp for everyone. Once I got the mesa subway d-800 and subway 115 I quickly realized I could get close to a lot of other class d amps sounds with the deep switch off, but turning on the deep switch just added another dimension to the sound which made it more to my liking as someone who came from using bigger rigs. It doesn’t “feel” like a small lightweight rig. Still using it years later and have no intention of replacing it unless it stops working.