Warning! Anyone who has a working Theremax, and loves their Theremax (or any other PAiA product), is likely to be offended by what I say below. Whilst I feel strongly that what I say below is true, it is all, nonetheless only MY PERSONAL OPINION.
The story I have heard about PAiA:
PAiA started life as a tax fiddle to fund their hobby, they were hobbyists, and realised that by becoming a company, they could offset all their expenses against tax. In order to qualify for tax relief (as I understand it) they had to have products on sale - so they advertised stuff with no expectation of sales, and were shocked when people bought (their rubbish).
I cannot be sure of the authenticity of this story.
IMO, they started as hobbyists - and thats fine, many good engineers do.. What isnt fine is when they dont move on, stay hobbyists, but for some reason which I fail to understand, lose their hobbyist "status" and get taken seriously.
And, IMO, this is PAiA - A "company" which (from what I have seen) has never put a sound design on the market. Any non-hobbyist (and many hobbyists as well) who is competent in electronics and looks at a schematic of any PAiA product (or at least any that I am aware of) is filled with horror at the utter incompetence of the design - and its not just about "cutting corners" to save cost - often the incompetence actually results in inferior circuits which cost more than an equivalent competent design.
" still had a small square wave component mixed in which is not pleasing to my ears... I don't know if I had to do that because there is something wrong with my assembly or not but it will probably cause problems in some other way I have not considered. " - No, there was no fault with your assembly - that circuit is one of the incomprehensibly bad PAiA designs, and is typical of the crap they throw together.. its not about cost.. getting a square wave which doesnt pull down the supply and leak in the mix is easy, and could have been done well at lower cost..
Somewhere back in the TW archives, there are a few postings related to the square wave comparator, in which all the technical people involved in the discussion agreed (a rare event, LOL ;-) that the Theremax was a turd not worth polishing.
Fred.