so the only way I could ever own a H9 Max again is to buy a H9 Max?
Yes. If I were you, I would get an H9 standard. Then you will have 13 (you purchased) + 9 (come with H9 Harmonizer) +1 (a new coupon) algorithms, which should cover most use cases IMO. If you need extra a couple of algorithms, you can still buy them separately.