Splitter -- One preamp to two amps. What to use?

cat_doorman
It was I who was missing something. I was thinking I needed two inputs into each amp, but you are right. I guess I only need one channel on each amp if I bridge. This would also solve the impedance problem. 

I guess the next question is How does bridging affect sound quality and is it better or worse than running two stereo amps? 

Thanks Guys!

Your best option, ime and imo, and this is because you have two exact stereo amplifiers, is to passively, vertically biamp the ARs. What this entails, is each amp drives one speaker. Each amp would have one channel feeding the bass, the other channel of the same amp feeding the midrange and treble. Repeat for the other channel. One rca channel from the preamp to each amplifier, with a y splitter going to each the left and right input of the amp. All 4 speaker wires should be the same ( same for the woofers, and same for the midrange and tweeters ). Y connectors would have a 1 female rca,  accepting from the preamp cable, to a pair of male rcas, going to each channel of each amp. Enjoy ! MrD.

I was just about to post the following when I saw MrDecibel’s post above. Great minds think alike :-)

In most cases a bridgeable amp will not sound as good in bridged mode as in stereo mode. A major reason for that is that in bridged mode the amp will "see" a load impedance equal to the speaker impedance divided by two. And in this case it appears that the NAD 2600 is specified to drive impedances of 4 ohms minimum (in stereo mode), so if the impedance of your speakers is less than 8 ohms, or if it has a nominal impedance of 8 ohms but dips down to significantly lower values in the bass or mid-bass regions (where lots of energy is often required), that issue is likely to be particularly significant.

Also, like many NAD amps your 2600 has considerable dynamic headroom, and is specified for stereo mode as being able to provide short (20 millisecond) bursts of at least 380 watts into 8 ohms and 450 watts into 4 ohms. So the power increase that bridged mode can potentially provide (if the impedance of your speakers is not too low) is unlikely to be needed anyway.

I suspect that a better approach would be to change from the present "horizontal" biamp configuration you are using to a "vertical" biamp configuration. In that configuration the amps would be used in stereo mode, but each amp would be dedicated to a single speaker. One channel of one amp would power the highs on one speaker, and the other channel of that amp would power the lows on the same speaker. When two identical amps are biamped a vertical configuration is generally considered to be preferable to a horizontal configuration. The reasons include reduced inter-channel crosstalk within the amp (since both channels process the same signal); the power supplies in the amps just need to support bass frequencies (which typically require a lot of energy) for one channel rather than for two; and a vertical configuration may make it possible to locate the amps close to the speakers, in which case both the sonic effects and the cost of the speaker cables may be reduced as a result of their shorter length.

What I would suggest is that you consider implementing a vertical biamp configuration by putting a short y-adapter cable at the inputs of each of the amps, and for each channel running a single interconnect from the higher quality output of the preamp to both channels of the corresponding amp, via the y-adapter. Looking at the impedance numbers for the amp and preamp in this particular case there will not be an impedance compatibility problem, if a single preamp output is used to drive two amp channels.

Good luck. Regards,

-- Al

Yeah, what Al said !

You guys!  What perfect responses! Thank you! I guess now my only concern is the possible degradation of signal flow at the y-adapter. I'm running audioquest Waters interconnects and would hate to lose the quality at the Y. Suggestions? Female input into two male outputs takes wire. 

Michael