Hi ksweiss,
I’m not Lee but I thought I would pitch in my 2c worth.
Clocks are quite sensitive to, among other things:
- EMI (which is generated by several components inside our DACs)
- Vibration (which is generated by things like transformers)
- Heat (which is generated by devices like transistors and regulators)
Hence the improvements we see in jitter performance when we place the clock crystals in a dedicated chassis. So the question of where to site the clock boils down to how much it might be exposed to the above factors.
We pay close attention to all the above when designing our products, so the amount of EMI emitted outside the chassis of one of our DACs for instance is minimal, as is the ingress of EMI from the outside. Although the chassis is an integral part of the heat dissipation regime (you will feel that the chassis becomes warm to the touch) the amount of heat transmitted to a stacked component (especially one stacked below) will be fairly minimal. Each of our chassis has feet designed to provide mechanical isolation in both directions. Etc.
So how much difference will stacking a DAC on top of the clock make to the above factors? You can actually measure the temperature before and after via Mosaic or the web interface, and even measure vibration using something as simple as an iPhone app. My guess is that placing the clock on a well isolated shelf on a decent equipment rack will have a greater positive effect than subsequently stacking a DAC on top of it will make to the detriment.
So I suspect that this is a case of marginal gains. But if you test, please report back on your findings!