Will you be able to load the EQ via USB - say from an app like Roon or REW? Or will you have fiddle with coloured balls? And will the volume be controllable via USB also, so that music players like JRiver and Roon can set it?
This is an extremely good point.
Since Mojo 2 uses the EQ mechanism to effect volume control, it seems reasonable that Quarter M Scaler would implement volume control in the same manner.
Honestly, though, I doubt Rob will implement any form of communication "over the wire" for either EQ or volume, to support JRiver or Roon or an uploaded REW profile.
I do hope that Quartet M Scaler has a display of at least DAVE's capability and also includes sufficient buttons to make the setting of EQ more transparently comprehensible without a manual than is seen with Mojo 2. Clearly Mojo 2 is constrained by case size and costs, in general - but Quartet M Scaler shouldn't be.
Well, in any case, the die is cast. I don't think there's a chance of substantial new capabilities being added - we saw such an improvement with Blu Mk 2 where the USB input was added due to popular demand very late in development. But this seems unlikely to be repeated with Quartet M Scaler.
Though I think Rob does use JRiver...
Currently Hugo M Scaler provides the DX volume command interface - the user is able to specify a volume level, but no change to the audio data is made. Instead the connected DAC is expected to take this volume command and act upon it within its own implementation of volume control.
All future DACs in the mould of Hugo 2, TT2 or DAVE will need to have volume control as part of their built-in functionality in order to enable them to operate stand-alone. So all of them will require some form of user-selectable volume control. By this I mean to say that while a stand-alone DAC might be considered to be a slave of Quartet M Scaler due to it sending music data to the DAC having EQ and volume control, a DAC with a headphone socket must be fully operational in a stand-alone form.
I hope that Quartet M Scaler retains DX volume control capability for use with DX amps, for what it's worth. I would ultimately like to exchange my power amplifier for a DX one. It can be argued that volume control capability within Quartet M Scaler obviates the DX command of volume to a DX amp.
On the other hand there is a more complex scenario for EQ: when a user wants to deploy multiple power amplifiers for an "active speaker crossover" capability, there is a need for each channel of power amplification to have its own bandpass settings. In this scenario the music data cannot be EQ'd globally for all of these amplifiers without having many channels of output from Quartet M Scaler.
A possible solution would be that the DX command vocabulary is enhanced to communicate EQ (high pass, low pass, bandpass) to multiple power amplifiers. Implicit in this, it appears, would be the need to daisy-chain these amplifiers to take stereo digital outputs from Quarter M Scaler. Each of the daisy-chained amplifiers would then need to be instructed to subscribe to a specific channel of EQ setting. e.g. in a 3-driver speaker there needs to be 3 channels of EQ settings per speaker (6 channels of amplification, overall, for stereo). In each daisy-chain (defined as being either the left or right music channel) each amplifier has to be configured to subscribe to one of the low, mid or high EQ bands corresponding to bass, midrange or treble drivers.
As I understand it, Mojo 2 performs EQ/volume after WTA1 has been processed. Conveniently all future DACs and DX amps will have equal access to "post-WTA1" data, whether they are stand-alone (no M Scaler) or connected to either Hugo or Quartet M Scaler. So it seems reasonable to presume that all future DACs will have the ability to perform EQ in the same way as Mojo 2 currently does, whether or not there's a scaler providing data.
This would also mean that an EQ capability (for active speaker configuration) in DX amps would be the sole responsibility of the DX amps and would not be directed or effected by Quartet M Scaler. Daisy-chaining would still be required, but each DX amp would be solely responsible for the EQ tailored to the speaker driver it powers.
The user might perform "global EQ" for the system as a whole, using the EQ capability of Quartet M Scaler. Each DX amp would then be responsible for the driver's filtering...
