Whatta Ya Think About Hsu Research Subwoofers?

I’m in the market to add one or possibly two subwoofers to my stereo set-up.  I would like to spend $1,000 or less per unit, and that puts some of the higher-rated units out of reach.  I came across an ad for Hsu, which I had not heard of before.  I didn’t want a Chinese product and it turns out that Hsu Research is based in California and founded by Dr. Hsu, who has a Ph.D from MIT.  Audio reviewer Steve Gutenberg gave one Hsu product a positive review.  I was wondering if any of you have experience with Hsu and could share your impressions/recommendations with me.

My existing set—up is:  Parasound P5 pre-amp with Parasound A21 amp;  Martin Logan 60XT tower loudspeakers.  Thanks!
I'm not sure brand mixing is a good idea as you have to know that when you're out of the room the things are going to argue with each other...nobody wants that. 
Wolf_garcia!  Of course you’re correct.  How could I be so blind to the perils of “mixing” in this woke age?   I’m blessed that you spoke up while there is still time to avert catastrophe!  I am in your debt Sir!  😝
HSU  does charge shipping so do not forget to factor that in when comparing The SVS Gloss Finish Adder
HSU Makes a well regarded Sub[I had a STF-1.great bang for the buck!]

@bob540, I have a pair of the original passive (no plate amp, but a passive x/o proving low-pass filtering is included) HSU sub, the HRSW10 (Rosewood veneer). They’ve been in storage for years, and I just pulled them out of their cartons. The foam surround on the 10" woofer in each sub has disintegrated (damn California air pollution ;-), but all else is fine. HSU has replacement woofers, so if you want the HRSW10’s cheap, let me know and I’ll list them.
I’m not familiar with those subs.  I looked them up and they appear to be from early 1990’s?  I have thus far only looked at powered subs — what are the difference issues involved in using powered vs. passive subwoofers?  

Also, one old forum I visited had a commenter (might have been Dr. Hsu himself!) who said the cost of replacing the subwoofers in old units might be close to the cost of new subwoofers. I would need more info. before deciding if I am interested in your HRSW 10’s.