Not sure what you’re asking? If Advantage doesn’t make a mono amp with the same wattage as the S150, we certainly can’t conjure one up for you.
If that’s not what you mean by “matching,” then any name-brand mono 150 watt@ 8-ohms amp you can find will work just fine.
If you’re determined to stick with the Advantage brand, then get the S-150 and use only one channel. It won’t hurt the amp. Or get the mono S-250. it won’t hurt anything if you don’t use all the available power.
Regards,
Wayne A. Pflughaupt