Are Pre-Amps necessary?

No surprise the Benchmark pre elevated your system's performance.    I have had a few DACs with volume and always thought a good preamp was the heart of a great sounding system

Very shortly I will be receiving a new amp,  it has two inputs which will allow me to A/B two sources...  or two preamps or a source direct vs preamp...  I will give direct connection another shot but I think it will still sound better with preamp in the chain.....

^ This will only inform you as to how it works in your system(s).  Not necessarily as a general rule.

 Ideally you’ll have a DAC with extra available bits for volume attenuation, with a voltage output that matches the input sensitivity of your amplifier(s) for full output. Such a combination will allow for full power output capability of the amp(s) and full range of the volume control without the risk of bit stripping from the DAC. Appropriate interconnects are also needed.

@twoleftears

Yep. All you need is a straight wire with gain and a potentiometer. Amazing that no one figured this out sooner.

well i had thought of that ages ago, but what has deterred me is done this way, i can’t easily get an extra $4,000 directional fuse in the signal chain -- and you know how those just make or break a system, ya???? 🤭🤭

Only if you want the best sound.

An excellent preamp is the heart of a system.  I went preampless for a while (dac direct to amps; berkley alpha dac and others).  NOTHING sounded as good as when I added a Jefff Rowland Criterion preamp.  It gave the wood winds wood wind; it gave brass the brass... It basically gave flesh to the musical bones.