An all Parasound system - Good idea?


My brother- in- law visited last weekend and heard my 2 channel system for the first time.  Slightly ocd, he spent much time online and emailed me last night to say he was going to put his own system together and was planning to buy all of his components from Parasound, in part because he thinks a single brand will optimze performance and compatability, and because he is enamored by the John Curl connection. To that end, he plans to buy  a JC2 Preamp, A21 Amp and JC3+ phono amp.

I have told him focus on  speakers first, then source components. That notwithstanding, is the "All Parasound " a good idea to avoid the possibility of components not playing nice together or should he not focus on brand loyalty and shop for "best in class" components instead?

sjtm
BTW - FWIW I have a one brand system (sort of) - Marantz PM-11S3 integrated amp and SA-8004 SACD player.  Others who know far more than me praised this amp and its phono stage. Pairs beautifully with my Focal 836v speakers.  My TT is a Music Hall MMF-9.1.  Thought about the Marantz TT, but it  is actually a Clearaudio product rebranded (great TT - but the MMf-9.1 gets the job done quite nicely)..

Not to change the subject, but as I write this, I am listening to the SACD of Elton John's Tumbleweed Connection - amazing album! If you have not played it in a while or are not familiar with it, give it a spin - guaranteed to brighten your day. The magic of music is that I may keep aging but the best music manages to stay timeless.
Don't believe that if it costs more or has a more prestigious name it is necessarily better.  Different?  Certainly.  Better?  Matter of opinion.  I just invested in a Pass Labs X150.8 stereo amp, which cost significantly more than my A21 and my Bel Canto REF100M monos.  In addition to these three amps I own a pair of Jungson JA-50 80 watt class A monos.  Every one of these amps provide serious enjoyment, all at different price points and with differing technologies.  Which one is 'better'?  You tell me! I prefer the Pass in the bass region and at low level resolution and detail retrieval vs. the other amps.  But it is not as 'sexy' or 'regal' as the Jungsons.  I can and do live with all of them, and gladly. I don't believe in absolutes, nor do I believe if you spend more you necessarily find something you end up liking more.  In fact, I believe sometimes if you spend 'too much' (or 'more') you actually end up disappointed because your expectations are not met based on what you paid. 
No absolutes in audio and I  respect everyone's opinion.  I've owned many components over the past 30 years. Nothing is as good as I have  now, based on my priorities and my ears. I could careless about the name or cost of a particular component. I have Monitor Audio speakers. They are not viewed as being high-end like Magico, Wilson, and a few other companies, but I have them anyway. My point is I never said anything about manufacturer or price determines what sounds good. I only said I didn't like the JC 2 and it's only my opinion.
Ricred, for you to describe the JC stuff as 2 dimensional, masks details(What??) and a big disappointment, there was something else at play.  It's not a case of different strokes for different folks.  Perhaps your speakers are a bad match for Halo gear, maybe you didn't break them in properly.  Your cables might be muffling things somewhat.  I know that I've cleaned all my cable connections and with deoxit and had the q-tips turn dark with carbon, and the sound improved afterward.   There had to be some other issue.

I mean, I guess one could prefer another brand, but not because the Halo stuff is 2 dimensional.