Need audio help (long)

[jmr3]

I am a very very inexperienced installer. I am running the stock (non HK) head unit, JL stealths, and just installed the Quart 325 setup. It is all being powered by an Alpine V12. Prior to the Quarts, the car had a set of Bostons in the doors (woofer & tweeter & Quart cross overs -- no mids) which came with it. They sounded less than steller so when I came across a used set of Quarts I bought them. I installed the Quarts and the cross overs that come with them myself this weekend. The mids get a static sound (almost like they are blown) from about 1/3 volume on up (below 1/3 they sound great). The tweeters and woofers sound great at all levels. Does anyone have a suggestion? Is it my head unit? How likely is it that the mids are in fact blown but the tweeters and woofers fine? Is there any definitive way that I can determine if the mids are blown? Anything else you can think of?

Thanks in advance.

John