Measurements and Analysis: Preamp Section
The green trace shows the frequency response via the analog inputs when engaged in a DSP mode and going through ADC and DAC conversion stages. As you can see, the frequency response is ruler flat past 20KHz followed by a sharp brickwall filter response rolloff at ½ nyquist frequency of 48kHz (96kHz sampling rate). The Denon upsamples all 44kHz signals to 96kHz / 24 bit as per their AL24 bit process. In fact, Denon's Advanced AL24 Processing handles up to 192kHz and 24 bit extension with real time interpolation.
Denon Advanced AL24 Processing Benefits (according to Denon)
- Frequency response expansion
- In addition to the bit extension by conventional AL24, the amount of information of music reproduction is expanded by performing interpolation on a real-time axis with original high-speed signal processing technology.
- Real time variable filter
- In order to perform reproduction optimal to high sound quality, Advanced AL24 detects signal changes in real time, where a trigger is generated to change dynamic filtering
The light blue trace represents analog output frequency response of the main channels via analog input signal with no bass management applied. The green trace represents the bass management applied with a crossover setting of 80Hz. Notice that no A/D to D/A conversion stage took place to apply bass management as indicated by the lack of brickwall filter response at high frequencies. At first, I didn't understand this until I pinged Denon and they informed me of a completely independent bass management system done in the analog domain to ensure a true analog signal path was maintained. Audiophiles and fanatics can rejoice. Now you can have a true analog bypass with proper bass management (if needed). This is a truly incredible and thoughtful feature.
Note About Pure Direct Mode
When configuring Pure Direct mode, I recommend setting it to the "Basic" bass management option first so it copies the front channel distances that were established during auto setup. Afterwards, you can select "Custom" if you desire to change the crossover setting or even the distance compensation. Note however that distance compensation in Pure Direct mode and all modes for that matter can be fine tuned to 0.1ft increments if you enable this accuracy in the main speaker distance set-up menus, otherwise it will default to 1ft resolution (the typical limit of most costlier processors).
