Some have had longstanding problems with whine (for instance, see edsmiata's thread "I give up!!!") OTOH I've had the empeg in two different cars. In the first one with first 2 amps and an additional HU, then with 2 amps only and lastly with just 1 amp. In the second car just with 1 amp - never a problem with ground loop whine. .

/Michael