Emile, here's my thinking on whether to retain, or not, the Nordost QNET switch in series with the Taiko switch.
1) The first consideration is that I have a single ethernet wall port coming from the cable modem 50 feet away to the part of the house that has the music room. I need to access the ethernet in the music room for 2 purposes a) the Taiko switch and b) an ethernet line to my smart TV. Since the Taiko switch does not have any spare ports, I'm essentially one port short so the Nordost switch will be useful in providing a port to send ethernet to the TV. If there is an alternate method that is simpler (a simple splitter at the RJ45 wall port?), please advise.
2) The real attraction to retaining the Nordost switch might be in the area of noise reduction, which always emerges as a key consideration for your approach on how you intend to optimize the entire signal pathway from ISP to the Extreme. Here's a partial factory description of the Norsdost Switch:
Each port on the QNET is optimized for its application. Three of the five ports are auto-negotiated 1000BASE-T (1 Gbps) capable, which should be used for the router and other generic network devices. The remaining two ports are fixed to 100BASE-TX (100 Mbps), a speed at which internal noise reduction is possible, making these ports best used for primary audio servers/players or external media sources.
What is unclear is exactly what they mean when they say"internal noise reduction is possible"? Does this mean that noise reduction in those ports only occurs on Tuesdays? Sunny days only? Any day but only at a certain time? Are special incantations required? I have no clue what they mean when they say "noise reduction is possible" but the question is, if noise reduction is indeed possible by using one of their 100Mbps ports, could this be advantageous since it falls in line with your hypothesis that noise reduction in networks in general, seems to be a good thing! I think the only correct answer at this point is- nobody knows, at least not yet. Thus, since putting the Nordost switch in series with the Taiko switch is easy to do, there's little down side to trying it both ways and seeing if any differences can be heard. Would I be thrilled not to need the Nordost switch at all? You bet. Bye-bye Nordost = found money!