Originally Posted by Krazywaffle
Based on manual it is my understanding that it is better to set input to 24 bit if digital source EVER provides 24-bit. Being that my Mac mini music server does sometimes provide 24-bit audio and my PS4 Pro can provide 24-bit DTS bitstream, it seems best to have it set to 24 bit input (to accept 16-24 bit inputs) and upscale everything to 24 bit (when needed) before outputting to 568.2mm set to 24 bit input. Or is this an incorrect understanding of the manual?
If the 518 is set to 24P24, 16-bit (or any) input will not be enhanced to 24-bit, it will just pass straight through, other settings like Gain etc. will still have an effect.
It may be worth setting up separate sources (some call them phantom) for the different files and switch to suit.

Originally Posted by Krazywaffle
And with using “Gain’ setting instead of “Emphasis” setting? Emphasis seems to be the recommended setting for most media types.

Emphasis will change the frequency response, similar to a RIAA curve on vinyl, dolby NR on cassettes, in effect boosting the number of bits for high frequencies. But it should only be used with DACs that can de-emphasise (preferably in the analogue stage) and I don't think Meridian processors do.
Gain is useful for upping low output signals, optical out on a TV is a normally a good candidate, most are 8dB down.
Both emphasis and gain can cause clipping of the digital signal.

Originally Posted by Krazywaffle
Also, the last two settings in Config menu aren’t disused in manual: (1) DA Y/N (currently set to Y as presumably DA means “digital audio”?) and (2) DTSXX (currently set to DTSCD).
Info I had in my notes from years ago:
If you have a Meridian 518 Digital Processor, this will de-jitter a DTS signal for optimum sound quality.

However the resolution enhancement features of the 518 are not appropriate as DTS is a compressed digital stream, not standard digital audio. Hence your 518 should be switched to Bypass mode prior to listening to a DTS CD or LaserDisc.

There is an upgrade to the 518 software, Version 1.2, which allows it to detect a DTS stream. In this case, the 518 automatically selects Bypass when DTS is detected.

Version 1.2 adds four DTS modes to the 518 which can be assigned to sources in Config. The modes are:

· DTSMU – 518 mutes on receipt of DTS (used when 518 is a preamp).
· DTSCD – detects DTS with a normal strategy and selects Bypass.
· DTSLD – detects DTS with a rapid strategy and selects Bypass.
· DTSMA – mastering processor mode ignores DTS.

These can be selected according to Type as follows:

· Type 0 – all sources DTSMU
· Type 1 – all sources DTSCD except DVD and LD which are DTSLD
· Type 2 – all sources DTSMA

Originally Posted by Krazywaffle
Firmware is version 1.22 but might have a lead on an upgraded ROM chip (presuming it is worth the effort to upgrade to 1.25?
I thought 1.22 was the final version?

All the best,

Steve