@devinplombier I have used a sub with the SR1a. At one time I had my KEF KC62 sub on a bar stool near my ear level. I was just trying the sub on the stool for kicks. I now have the sub on the floor.
Office System 2 | Virtual Listening Room
The KC62 sub is fast and can keep up with the fast SR1a. This sub is for music and not HT. It was good and definitely added to the low end of the phones since the SR1a is open. However, one of the reasons I use the SR1a is so as not to disturb others late at night and a sub booming away does not help keep it quiet.
I used to own the RAAL CA-1a and that was not an open baffle headphone and had a lot more bass and was a RAAL ribbon phone. However, I gave that to a family member since I do not miss the bass on the SR1a and the only purpose it served was that I could listen in my bed with the CA-1a and not the SR1a. The review I linked to explained how the SR1a moves around if you bend your head too much.
I am friends with Danny Mckinney who was the co-designer of the SR1a with Alex in Serbia. Danny recently told me that he is designing a bass module specifically for the SR1a. Something similar in execution as how I used my KC62 sub. Danny is about to release an open baffle 2-channel speaker, and it was an incredible sounding unit. The bass was the best I ever heard. He is going to use the same bass driver for the SR1a bass module.
If you are interested in getting the SR1a send me a DM and I can help advise the amp to drive it. The SR1a is a bright phone so care is needed. I have the best amp for it, the RAAL VM-1a. However, relatively soon there will be new competitors for that title.
Over the past 5 years, I did amp rolling for the SR1a. I loved this phone so much that I wanted to get the best sound from it. I must have spent $40k (but sold about $30k). It is a lot easy these days because of a new amp adapter called the RAAL TI-1b, when I amp rolled that device did not exist.
There is also the $7k - $10k RAAL Immanis that is considered by most the best RAAL phone. It is not open baffle like the SR1a, so I like the SR1a more. However, the Immanis is a tour de force and on my radar because I no longer have the CA-1a. The bass on the Immanis is supposed to be as good as it gets for headphones. I had this phone in my home for about a week and the bass was terrific.