+1 on the surprise. The rig was sounding good fed by ethernet from switch to T2. With the gigaFoil in place, I just haven't noticed anything getting better. I've tried Avanti Vivace from switch to gigaFoil and WW Starlight 8 from gF to LUMIN and the other way around without much difference. I believe they are both fine cables.
Okay, perhaps some technical background info would be helpul here to put things into context to help shape "domain understanding", as it were. The reason that placing or installing an "optical link" e.g. a Gigafoil, between say, a router or switch, and an endpoint, e.g. an upstream switch, network bridge, or streamer to improve audio quality is that many "consumer-grade" or "generic" networking devices are powered by very cheap, generic switch-mode power supplies. These generic power supplies put what is known as "low-source" and high-source" impedance
leakage current onto networking cables, e.g. Ethernet cables, etc. This leakage current is actually AC, alternating current. The leakage current causes what is known as "threshold jitter', which is
not the same as random jitter or deterministic jitter. The main problem that threshold jitter causes are timing errors, and our brains, which are quantum computers, are
exquisitely sensitive to timing errors when listening to music; we can discern timing errors in the
picosecond domain, which is why high-end digital audio devices must utilize
femtoclocks.
What the optical transceivers are doing when they convert the eletrical signal to
light, and then back to an electrical signal again to at the destination end. The reason that installing a "run of optical" mitigates this is because quite simply leakage current cannot pass as "light". There is nothing "magical" or "woo-woo" about these optical transceivers, they are standard networking product built to a consistent set of standards.. And this is why you
don't need to buy a Gigafoil and LPS to implement a run of optical between a "dirty" switch or router and an audio networking endpoint.
Exactly the same functionality can be obtained by using a couple FMCs (e.g. TP-link), some quality optical transceivers (e.g. Finisar or Planet Tech), a run of LC/LC optical fiber, and a coupla $12 Jameco Reliapro wall-wart style linear power supplies.
Physics does not care one bit about WHO implements functionality (what we can in engineering,
a transfer function), only
HOW.
The reason that "audio grade" FMCs, e.g. those in the Sonore OpticalModule Deluxe, and switches e.g. EtherREGEN, SOtM sNH-10G, Melco, etc., produce higher audio quality than "generic" FMCs is they have better RJ45 jacks with better quality isolation transformers and better quality clocks. The better quality clocks also reduce
phase noise, which our hearing is also very sensitive to.
Now, coming back to your setup, if I were to hypothesize, it's your Lumin T2 that is mitigating or attenuating noise, threshold jitter, timing errors, or phase noise from the switch. Lumin is
really good at this; I've been very impressed with how thoroughly Lumin
thinks things through and then implements effective designs and functionality. For example, they very likely are using a very high-quality RJ45 jacks with quality isolation transformers and a very good clocking system in the T2. These solid design factors and engineering solutions likely explain why you're getting such good results with your setup from the switch to your T2.
