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Parasound A21 question - can I use both balanced and unbalanced input on the amp?

In my second system, I would like to double the duties for both HT and music. For preamp, I'm using a Cambridge Audio 851D, which unfortunately doesn't have any HT bypass or even analog inputs.

Originally, I was thinking that I might be able to connect the pre-outs from my AVR to the 851D. And then from 851D to Parasound A21 via balanced/XLR connection. But the problem is that my AVR has only RCA pre-outs and the Cambridge has only digital inputs.

Another option that comes to mind is something like this:
1. Cambridge 851D --> Parasound A21 via balanced/XLR -- for music listening
2. AVR --> Parasound A21 via unbalanced/RCA -- for movies

Is this even possible? Assuming it is, can this cause any potential harm to the amplifier if both balanced and unbalanced inputs are connected to different sources? What should I set the switch (Balanced/Unbalaned) to on the A21?
128x128arafiq
tls49's avatar
tls49
1,351 posts
 
Thanks Al, for your comment on my suggestion. This type of adapter can be found for less than $10 on either one of those huge online shopping sites, however, I chose to show the Gefen because I have experience with a few of their video products and they always worked very well with no signal degradation. The Gefen was the only one that showed specifications for SNR, THD, Frequency Response, and Crosstalk, which are reasonably good. Also, B&H Photo has a 30 day return policy.

Arafiq, if you want to look at the cheaper ones, just make sure it is the A to D, and not D to A. The majority of the cheaper adapters available are D to A. I did notice a review about someone being sent the wrong one.

And if you try this, I hope it works well, and glad to help.

arafiq's avatar
arafiq OP
1,665 posts
 
almarg, thanks for the detailed explanation. I didn't realize the impact of impedance even when the unit is turned off. I looked at a few other adapters on amazon but it seems that the Gefen recommended by tls49 is a better choice. It's a bit more expensive but looks to offer more in way of quality and has decent reviews. 

However, having said that, I am now in two minds whether to just stick with the Parasound P5 and return the Cambridge 851D to AudioAdvisor as I'm still within the 30 day return period. I only bought the 851D thinking that the DAC is considered to be much better than the one in the P5. Since I mainly stream my music, it made a lot of sense. But the HT bypass, bass management and tone controls on the P5 are features that are quite useful. I don't know if improvement in the DAC quality is worth losing the other features of the P5. Tough decision.
rgraddy
1 posts
 

dbphd, you said:

The A 21 is a very nice amp.  I use mine with balanced input from an Oppo 105 to drive a pair of KEF LS50s with excellent results.  The Oppo does double duty as a disc player and processor, and does it well.

I also have an Oppo bdp-105. Mine directly feeds into a Parasound A51 amp. Since the Oppo has XLR outputs only for the main R/L channels, the Oppo's surround outputs must necessarily connect to the A51's unbalanced inputs. Using that mixed combination, I have the balanced/unbalanced switch set to balanced. Would it be better to just use unbalanced connections on the main R/L channels? In that case, the XLR's would not be used at all and there would be no question as to where to set the balanced/unbalanced switch.

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