Speakers for 4 x 15 watt Nakamichi amp ?

I am newbie putting together a somewhat retro system for my "almost" new 1982 Mercedes 240D (76,000 miles). Nakamichi TD-400 head unit Nakamichi PA-150 amp (4 channel, 15 watts/channel) Rear speakers MB Quart QM 130.03 KX Front speakers - still looking for MB Quart 4" seperates I do not have the amp installed yet (just bought it on eBay. Will replace 2 channel Clarion junker) My problem is specifications. They are often quoted as "30 to 80 watts". But 85 (or 87 db) with 1 watt 1 meter away. 85 dB is WAY more than I want (mainly classical music). Now, even if Nakamichi is VERY conservative, their amp will never put out 30 watts. One installer told me that the lower quality MB Quart Reference speakers would work better with low power than the higher quality Premium series. I kind of doubt that. Any thoughts ? Also, what is the difference between the PSD & PCD series speakers. The first letter in MB Quart speakers is D = Discus (low end), Reference/Referencz (medium low), Premium (medium high) and Q (high end). The last letter is sequential (E is current series, D before that, C even earlier, etc.). But the middle letter means ? C & S ? Thanks, Alan1982 Mercedes 240D, Manual Trans, White w/tan interior

76,000 miles Pristine

Nakamichi TD 400

Nakamichi PA 150 (4 x 15 watt)

MB Quart QM 100 KN-S & QM 130.03 KX speakers

he may have said that the lower quality speakers would have worked better with less power because the high quality ones are fitted with larger magnets and designed to handle more power   the sound won't be too much different   MB Quart is a good companyAlpine CDA-9847---Alpine MRP-T220---Eclipse 36201---6.5" Type S Components---6.5" Type S Coaxials---2 10" Thunder6000's Isobaric