I thought i would post my final thoughts on the Parasound.
I had a chance to take one home along with the Anthem MCA20 for Christmas. Both are now heading back to the store before the return policy expires.
The Coles notes version of my demo on these amps ( it's real easy).
THERE WAS NO DIFFERENCE IN SOUND.
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I actually had setup a proper A/B test for these 2 units (mono setup, 2 speakers, one amp powers each speaker so the balance knob on the preamp could be used as the 'switcher').
You know what i found out?
That my left ear hears differently than my right (not an odd thing though) and when i switched amps:speakers to L&R or when i turned my head 90 degrees to switch and listen with only my left ear pointing towards the speakers, all the perceived differences between the amps went away or were reversed!!
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Secondly, the 2 amps had to be calibrated for the A/B test such that the volume output was identical. The volume on the preamp produced a louder volume through the Parasound than through the Anthem amp. If it were not for the gain selectivity feature on the Parasound amp, lowering the gain to match the volume of the Anthem would not have been possible. In my first run around, i actually thought there was a sound difference but realized that one amp just sounded louder than the other. After calibrating the decibels, this was no longer apparent. (I can only speculate how many ppl have auditoned amps in their home and not accounted for such a variable but then reported one amp is "more robust" or "more punchy/powerful" etc. than another.)
On the other side of things, i did do my best to find any type of flaws in either unit such that i could try to rank them in my short selection list.
Here is that list of things i found:
Parasound Halo A23
gorgeous case and lights, nice design
great features (just loaded -balanced or unbalanced connections, loop out connections, 3 methods for turning it on/off, carry handles, gain selectivity knobs to adjust for preamp signal strengths and a ground loop switch)
runs pretty hot when pushed
more pricey than Anthem
auto signal detect on feature really needs a strong signal to get it to work, below volume 7 on my preamp (scale of 0-35) would actually cause the amp to shut off thinking there is no signal. This was kind of annoying when playing music relatively low but at least the alternative was to use the trigger switch method or find a preamp that puts out a stronger overall signal .
larger build, very solid and huge internal parts compared to the Halo
good heat dissipation
cheaper than Parasound ($1500 for the MCA20, $1600 for the Parasound but i could have haggled a bit for the Anthem dropping the price)
auto signal detect feature worked better than Parasound
Canadian company (i prefer to support national economy if the item is of good quality rather than buying something built overseas)
real boring look and case, not all silver (silver face, black case compared to the Halo which was all done in aluminum finish)
power plug does not have a ground plug (kind of surprising)
not as many features as the Parasound ( it had balanced and unbalanced connections and the 3 method on/off switching and that's it)
The Halo Hum as previously referred to was still evident, however the Anthem unit produced a similar sound although a bit different. In previous tests with a Coda amp, no hum was really evident. Upon changing the preamp (Denon) for my a/v receiver (Onkyo) the hum was nearly non-existant for both the Anthem and the Parasound.
It is very possible that the Denon is responsible for introducing a background noise into the signal although it was not at all noticeable once music was playing. The noise floor of the recording is easily more than double the sound of any background hum. The use of the Onkyo clarified my concern about the alleged Halo Hum. There really is none.
All in all i would probably buy either unit but my wife preferred the Halo over the Anthem based solely on aesthetics and its smaller size. I would have preferred a larger sized Halo unit as the A23 model runs a bit hot for my liking but the features it has are darn nice. However, b/c the Halo is priced so high and the auto detect feature is a little weak, i would buy the Halo unit over the Anthem ONLY if i can get it for a good price used, perhaps in the $1200-1400 range, but not at $1600 plus taxes (all Cdn values).
If i can get a good silver Anthem for about $900-1200, i would buy it instead. It is NOT worth the $1500 considering the $100 extra for the extra features of the Parasound Halo (using the retail prices i was quoted before taxes or haggling).
Both units sound excellent and powered my Tannoy Definition D700s with ease. There was never any clipping or overheating issues as indicated in sound or by the unit diagnostics even after an hour of 105dB playback (2.4 metres, approx. 8 foot measured distance).
If you want a no frills, heavy built, cheaper unit but also with more simple aesthetics (blander look), the Anthem was great.
For a bit more class, several more features and a slight step up in price, i would take the Halo, but NOT unless its price was very less than retail due to the auto detect issue and smaller heatsink/internals.
Their price compared to many amps in this power range is extremely good. I certainly would recommend either one.