Having spent some time in both in Netto and in Richer Sounds, I feel qualified to take this on. Netto sells brands you've never heard, usually of questionable quality. As opposed to, say, Lidl, where you get brands you've never heard but some of which may be of decent quality. In Addition, Netto 'sells 'em cheap' but 'piling them high' isn't of paramount importance. It's just cheap. Richer Sounds rent small shops and fill them floor to ceiling with brands you have heard of. They can sell their stock cheaper because of lower overheads and by utilising their buying power to snap-up the massive surplus of unsold hi-fi gear floating around out there. That said, I don't know how they fare these days since the boom in online shopping. Just don't buy their own-brand stuff. It's shit.