'not a good idea, XLR line level outputs are optimized to drive loads with an impedance of 600 Ohms or greater, and speaker impedance can be as low as 4-6 Ohms (yes one hundred times lower). This means to achieve the same voltage level, 100 times as much current is required, so although the peak voltage that a power amp can output is not too much higher than the DA10’s XLR outputs, the XLR outputs do not have the “juice” to back it up and produce the needed power.
Power amps also have very low output impedance, and because the output impedance of the DA10 XLR output is optimized for stable operation with relatively high cable capacitance, a significant amount of the voltage available would be lost in the output resistors of the XLR outputs before it even reached the speakers. This voltage division would also be frequency dependent because the speaker’s impedance varies with frequency. So the frequency response of the speaker system would also be degraded.
The last factor is “damping” which is directly proportional to the amp’s output impedance. This has a lot to do with why a seemingly over-powered amplifier will make speakers sound better than a low power amplifier, even at low volumes. The lower output impedance of the larger amp allows the amplifier to maintain tighter control of the motion of the speaker cone than a higher impedance amp, keeping the speaker cone from continuing to move in the same direction (due to momentum) after the audio signal changes.
Maybe with some unusually high impedance speakers…but with a rated (lack of) sensitivity of 84 dB and an impedance of 6 ohms, the Harbeth 40 monitors don’t fall into this category. Sounds like a bit of an urban legend (?) Either that, or they were saying that they drove their power amps directly from the DA10 outputs (which is a good idea).
