If I read the THX specs correctly, it is possible to mix and match THX certified speakers and still have a reasonably good sonic match because of the certification. Any comments? The reason I ask is that I am in the market for 4 surrounds to complement my M&K S150's but M&K's surrounds are a tad rich for me right now. Four SS-150's will run around $1600 whereas I can buy 4 Jamo D6 surrounds for $1000 or better yet 4 Atlantic Technology 350 surrounds for around $650. All of these are THX Ultra certified. Are these possible options or am I better off to bite the M&K bullet.