CD output voltage too high for preamp: what to do?

Best solution would be to have Ayre, or someone with the schematic to reduce the output of the CD player. I have no idea of the topology of the output circuit, be it discrete or op-amp based. I am assuming its solid state, maybe not. If it's tube, it should be quite simple. Barring that, I agree with Eldartford. A pair of high quality series/shunt metal film (or carbon comp.,if you want to go retro) resistors right across the solder tags of the CD input RCAs on your preamp will beat the snot out of adding another attenuator in series with your preamp volume control. Another attenuator adds increased capacitance; switch or slider contacts; and in most cases a reduction in the impedance your CD player has to drive. If you're interested I'll post the equation to determine the values.

The equation for voltage dividers is: (shunt/(series+shunt))=voltage reduction factor. VRF x Vin=Vout... (Vin/Vout)log20= db attenuation Put simply in your case, dropping from 2.25 to 1.5 is a voltage reduction of exactly 1/3. So, Series R would equal 1/3 of R total, and Shunt R would equal 2/3 of R total. R total =Series R + Shunt R. As concerns attenuation, R total may be any value you want. Obviously, if there are in fact resistors on the circuit board allowing further attenuation or gain reduction, use those. Hope this helps.

Almost forgot, as concerns input impedance; R total should be selected as to maintain yours. For instance if it's 50k and you plug a 50k attenuator into the inputs, your CD player will see a 37k load.( when set for 1/3 attenuation) and will vary over the range of the attenuator. And yes, if your source impedance is high enough, the upper frequences will be rolled off. Finding Rtotal is way too easy, it equals 150% of input impedance.(are you seeing that 1/3 relationship again?). Input impedance at audio frequences is almost purely resistive, so this can be measured with an ohm-meter. Alternatively, you could simply add a series resistor,to the CD input, of a value of 50% of input resistance and achieve the same voltage reduction. This of course would raise the input resistance by a third. All the above advice assumes a standard circuit design pratice used in almost all high end products. Mock it up first, with a set of male and female RCAs and resistors from Rat Shack, plug it in and listen, before taking the hammer and tongs to your preamp. O.K., now I'm done.

Restock- Beats me, unless they are designed for pro use. Sound reinforcement/studio equipment often employ a matched impedance interface to optimize power transfer. If thats the case it would almost certainly be offered with a balanced connection only.