That's interesting I didn't think my 140wpc 4520 had enough power to hit a limiter on a speaker rated for 200w hmm.
The good news is the 4520CI is actually rated at 150W! But you also need to keep in mind the conditions of the rating: it's minimum, continuous, into 8Ω, across the full 20Hz - 20kHz range, at no more than 0.05% THD and into two channels simultaneously. These conditions simply describe a "torture test" devised as a uniform, repeatable method of comparing the output of different amps.
However, the real demands placed on an amp and their output capabilities when hooked up to speakers and playing music is a whole different story. The figures on the 4520CI's spec sheet that arguably relate most closely to "real world" usage and performance is
Dynamic power (or short term peak power). Denon claim 190W X 2ch (8Ω) and 280W X 2ch (4Ω) for the 4520CI, so it's capable of producing "bursts" of power when called for that are almost double the 150W headline figure.
If you're listening at an Audyssey/reference calibrated +5dB master volume, that can equate to peaks at the listening position of around 107dBSPL (with a maximum -3dBFS input signal), for each speaker. (NB: Already beyond what the E55Ti's are designed for.) Now, in typical living rooms, SPL attenuates at what equates to about 3 to 4dB for each doubling of distance from the source. So assuming a 10ft listening distance, the attenuation will be around 5dBSPL. This means each E55Ti will need to be producing peaks of 112dBSPL (107 + 5) at 1m from the baffle for the required peaks at the listening position.
In the review above, Gene confirmed the E55Ti to have a sensitivity of 88dB/1W/1m, so 24dB (112 - 88) of gain is required from the amp to produce those peaks. This equates to, on average,
250W bursts of power being required from the amp to produce those peaks. (Use:
dB Power Ratio Calculator.) This amount of power is seemingly well within the dynamic capabilities of the 4520CI, but beyond what EMPTek's designers thought the E55Ti's tweeter should be exposed to.
If you can stand to listen to very "hot" recordings (approaching 0dBFS) at that master volume setting, and your calibrated listening distance is greater, bursts of power of over 500W (27dB gain) and up to 800W (29dB gain) could theoretically be called for.
