What kind of SPL levels do you listen at? Are you concerned to any degree about retaining your hearing? If you are harming your ears, the "glassy" sound could be associated with hearing loss. Hopefully not, but if you already have tinnitus, you may want to reconsider what you are doing, besides simply replacing tweeters.
Hopefully I'm wrong about your situation.
OTOH, if the problem is not hearing loss, there is a figurative world of difference between cheap and high quality drivers. You admit it yourself when you state the manufacturer would not accept the tweeters you are using. You are likely hearing that qualitative difference. One can attain harsh sound quite cheaply.
Hopefully I'm wrong about your situation.
OTOH, if the problem is not hearing loss, there is a figurative world of difference between cheap and high quality drivers. You admit it yourself when you state the manufacturer would not accept the tweeters you are using. You are likely hearing that qualitative difference. One can attain harsh sound quite cheaply.