Wall treatments “Asymmetrical”?

FWIW, I used a Stereophile Test CD 002-2 and a Radioshack SLM. Pretty straight forward, but unfortunately ’out of print’. You may find them used however. I’m sure there are probably others, used or new. Try eBay and Google if all else fails. On the subject of test CD’s, I also used ’The Sheffield/XLO test and burn in CD’ for set up and to really drill down imaging with a super CD, "Test Record 1" by Opus3. It came out on CD but I preferred the LP (or maybe I just liked my system). If your system is maxed out image wise you will be bowled over by the holographic image. A lot of different cuts from a bunch of Swedes in a perfectly mic’d set ups. Give you something to work towards. Probably have to get these on E-Bay.(?).

I’ll start searching and watching Yt videos on how to use a meter like that. Sounds like a fun project. 
thank you Newbee

BTW, FWIW, I just checked EBay and these items are available if you want them. I'm somewhat relieved, I was thinking of loaning you mine. :-)

@newbee thank you for your guidance and thought of loaning me your slm. I’ll find one on eBay. 

@newbee I found both an analog a digital slm on eBay. Is there a guide that can help me understand how to use this tool in dialing in my systems?