Parasound Halo P 6 2.1 Channel Preamplifier and DAC
March 31, 2019 § Leave a comment
“While the overall connections are similar to that of the former P 5 preamp, the P 6 offers some upgrades comparable to the modernization of the A21 to the A21+. I think that says a lot about Parasound’s ability to pack performance where it counts. The improvements move the cash-out-of-pocket (or Bitcoin-out-of-server) needle to $1495 USD, which is $400USD more than its predecessor. But I am happy to report that the combination of functional improvement along with the audible performance of the P 6 justifies the increase. Let’s thumb through the most notable upgrades.
First is a Burr-Brown analog-resistor volume control. Most volume controls on preamps work via a device not much different than a slide-whistle, at least in principle. As you turn the volume knob up, less resistive material is in the signal path, so a stronger signal moves through to the amplifier, thereby increasing the volume. The name of the device that performs this action is called a potentiometer, and it works “fine.” However there is a mechanical component that rubs against a swath of resistive material in a potentiometer. The mechanical contact, and the existing swath of resistive material is prone to wear and can become noisy over time. The solution would be to have a separate resistor for each step in volume, and it is available in the form of a device called a stepped attenuator. The swath of resistor gunk is eliminated in a stepped attenuator, but that pesky mechanical connection still exists whether by manually moving the contacts, or electronically controlled with costly relays.”