Accuphase Power Amps

Hi Simon,
When Nvp says, "has efficient speakers", I can only assume he's speaking of speaker sensitivity. As sensitivity of a speaker goes up, less power is required for volume and dynamic peaks.

The A-35 is rated at 30w/ch, and the P-4200 is rated at 90w/ch, or an approximatly 4.75db difference in power. So the P-4200 is capable of dynamic SPL peaks about 5db higher than those of the A-35 on the same speaker. Also, a 94db speaker with the A-35 will have the same capability as an 89db speaker with the P-4200.

I have listened to Accuphase Class A and Class A/B, and agree with the other comments regarding this, however to answer the original question, it would be helpful to know,

1) listening volume - low, moderate, or high
2) listening distance
3) amp you have previously used with the Spendors

I am assuming that some of your symphony recordings will have a wide dynamic range.

Simon,
Your Bryston is approximately 5db higher in power than the P-4200, or 10db higher than the A-35. I used an online calculator, that's available on numerous websites, with your speaker's sensitivity, listening distance, and power of the Bryston, and determined you currently have the capability for dynamic SPL peaks of 105db. Therefore, the P-4200 would have capability of 100db, the A-35 would be 95db, and the calculator confirmed this. Keep in mind that a dynamic SPL peak can be much higher than average SPL listening volume.

So, at your listening volume, what are the dynamic peak SPL's? Hard to say without measuring. It might be worth getting a sound level meter, and if you do, try both weighting scales and fast response.

Based on your comment about the Telarc recording, as the dynamic peaks could be as much as 25db higher than average listening level, I would get the P-4200. Again, I suggest you borrow or get a well reviewed sound level meter, certainly less than $100, and measure your current system. That way, you would know for sure, and the meter may be useful in the future.

Bvdiman, I do agree that Accuphase amps are conservatively rated, however I don't think the Spendor's minimum impedance is relevant. It is specified at 5.5 ohms, but Stereophile measured it at ~6 ohms, and showed it to remain above 8 ohms most of the time. Also, the calculator I used to determine the numbers in my post, factors in 3db headroom for the amp, which is a double of power.

Again, I agree an Accuphase amps' power will increase dramatically into lower impedance loads, like a 4 ohm speaker dropping to 2 ohms. The Spendor is just not that type of speaker load.

Bvdiman, sorry for any misunderstanding or if I was not clear, as I don't disagree, but absolutely agree with your comments. In the calculations, I did consider a 3db headroom for the amp, which would be 180w for the P-4200. For a 4db headroom, that would be ~225w, and for 5db headroom, ~280w, so just add 1db or 2db to the numbers cited in my previous post.

Also, I have experience with both Class A and A/B Accuphase and Bryston. Again, I recommend getting the P-4200, as I do agree with Dave_72 that it will smoke the Bryston in overall sound quality.