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Q Do the preamp outputs on A/V receivers work as well as those on a standalone preamp-processor? What functionality does one lose when using pre-outs on a receiver? —Ravinder Dhawan, Watchung, NJ

A Using the preamp outputs on an A/V receiver gives you access to all the same features and functions that you would get with a pre-pro, including surround sound processing, high- and low-pass filtering, and channel delay and level adjustment for individual speakers. You will also be able to use the receiver’s onboard DSP room correction (Audyssey, ARC, Dirac Live, or other proprietary processing). Some AVRs have additional processing channels you can tap when using their preamp outputs; such a capability will allow you to ramp up from, say, a 9.2-channel speaker configuration to an 11.2-channel setup by connecting an external stereo amplifier. Basically, by using the preamp outputs on a receiver, you are transforming your AVR into an A/V preamp-processor, nothing more, nothing less.

Where the preamp outputs on A/V receivers come up short compared with those on a pre-pro is the voltage level of the output signal. Since the individual amp for each channel remains connected inside the AVR’s chassis when you use its preamp outputs, the output level can be limited. This in turn limits your flexibility for pairing the AVR with certain external amps. Some AVR manufacturers — Denon, for instance — address this via a setting that disconnects the receiver's internal amp channels when the preamp outputs are used. One example: the Denon AVR-X6700H we recently reviewed features a “Preamplifier Mode” that, when selected, disconnects all of the receiver's internal amp channels. In doing so, it effectively raises the preamp output levels to as much as 4.8Vrms, which will let you run pretty much any amp you choose to pair the 6700H with at full power.

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