Alpine PDX?
 

I'm about to upgrade the amplifier in my car. I am going to go Alpine but am undecided on the series. I'm looking at the V-series (low end) and the PDX (high end) I am slightly confused as the specs of both amps are very comparable other than the SNR on the low end (yes low end) is higher. Is there a big advantage to the PDX othe than the regulated power?

P.S. I am looking for two mono's and a four channel.

Physical size and efficiency (compared to a typical class AB) are the PDX strong points.
Price is a low point and unless the two above reasons are of the utmost concern they're not worth the big pricetag IMO.

Apples and Oranges. The PDX amps are in a different class altogther. The V series really dosen't have a big power mono amp, but the PDX amps do. If your on a tight budget I would stick the the V series though. PDX can get expensive.

Alpine
 

Thanks fella's. For the mono I'm toying between the PDX 600.1 (600rms at 2-4 ohms) and the V series MRPM850 (500 at 2 ohms and 800 at 4 ohms) and the 4 channel I'm undecided between the 70x4 V series and the 100x4 PDX. I'm upgrading from 40x4 so both will be an improvement. Will SQ be similar?

SQ should be similar. The advantage to the PDX series is due to their full range class D ICEpower circuitry that they employ. This has allowed them to shrink the size of the amplifier, maintain power and not need to worry about heat as compared to a regular class D amplifier. This is Alpine first year with these types of amps, however it has been proven as Eclipse has used this amp topology now for 3 years. Pioneer Premiere amps also use this same very type of circuit topology and with the start of the 07 season coming, expect more companies to embrace it as well. While I have not played with the PDX series, I have played with the Eclipse for the last 3 years and have been thoroughly impressed by what they offer.