A couple of questions

[lofi-ear]

Hi'yall

Does the A21 benefit from using an active pre-amp? I currently use a passive one (Creek) and it sounds very good but could it be even better with an active one?

About A51 vs A21 in stereo listening, is there any reason to get the A51 over A21 if you listen to only 2ch music? In other words, does the A51 use all its power reservoir for two channels if only two loudspeakers are connected, or is the power evenly distributed to all five channels even if some of them are not in use?

Thanks in advance 8)

[Kal Rubinson]

I will not comment on question one as I am biased (in favor, generally, of active preamps).

As for the amp, there are two possibilities. One that the A51 has separate power supplies for each channel and, in that case, there will be little or no difference in power availability regardless of the number in use. The other case, more common, is one PS shared by all the channels and, in that case, using fewer makes more of the PS reserves available to the ones in use. This will result in a slightly greater power output but still limited by the design and construction of the output stage.

In other words, there will be a real but limited increase in output capability.

Kal

[Chris D]

Lofi, if you're only using 2-channels, you're really going to want the A21 over the A51. The A21 has a little bit more robust innards--check out the Parasound picture thread.

[Peter Nielsen]

About A51 vs A21 in stereo listening, is there any reason to get the A51 over A21 if you listen to only 2ch music? In other words, does the A51 use all its power reservoir for two channels if only two loudspeakers are connected, or is the power evenly distributed to all five channels even if some of them are not in use?

The A51 uses 5 modules with individual capacitor banks (32,000uF/channel). They are NOT interconnected in any way that matters (there's quite a bit of not-so-thick wire between the 5 modules).

The A21 has 50,000uF/channel. It's all on one heavy duty circuit board. Much more solid construction than the A51 if you ask me!

Consequently the A21 is more powerful and BETTER for stereo use than the A51.

If you have an A21+A51 setup, you should use the A21 for the L+R fronts.

(Side note: I have tested both the A21 and A51 to the limit with my Maggies. The A21 played to the clip limit without bad side effects . When the A51 clipped it distorted and ran out of juice so bad that it blew the fuses in the speaker. Ouch!)

[Mike_Schmidt]

Mr. Nielsen you know what I like about your answers. Its your informative response to each question being asked. Factual, not snake oil.

So thank you sir.
Schmidt