I'm reminded of eating out in Cyprus. A waitress describes the specials. They include lamb and beef. Ivette interjects that she's vegetarian. Without missing a beat, the gal proposes rabbit. Eyebrows arched, my wife explains that being vegetarian means she won't eat anything with eyes. Here I'd only have the optic cable which COS would include; and just their SFP ports. No other options would look back at me. No rabbits for vegetarians. No jumping down an endless hole chasing cotton tails. Still it's an excellent example. When you give a committed audiophile jack, he'll soon take the whole cable then everything connected to it. It's how we work. On which subject, reader Michael dug my hole deeper. He contacted COS with "do you have a recommendation for the fibre connection such as single vs multimode, SFP module brand or fibre preference?" Stephen's answer: "That's a very good question. Different modules and cables can affect the sound. Our plan is to sell the fibre-optic streaming module with two SFP ports plus 3m fibre-optic cable as bundle. Auditions of SFP suppliers and cables are still ongoing but most likely ours will be single mode." To which Michael added, "incidentally that's Lumin's preferred mode though they do accept multimode." I still didn't know what differentiates these modes and how that might impact sonics. Thankfully the optimum according to COS sets on their end. Unless inclined otherwise, clients won't need to give it another thought. But the subtext is crystal. Connector brands like Furutech, Oyaide, WBT & Bros. all have their fans. Why wouldn't the same apply to fibre-optic ports and the cables plugged into them? For the time being, suitable providers should mostly limit themselves to the pro sector until the usual suspects in ours see enough demand. Then pricing will drift or race upward as it always does in a sector that calls itself the high end.

If one is judged by kept company, the latest COS show sightings demonstrate high-class company.

On a related note, Michael sent me this Ed Meitner quote. Stereophile: "You don't believe in using an external word clock. Why? Ed Meitner: "Because I think it's the stupidest thing I ever heard in the audio business. It means you have a precision clock that must connect to a wire to connect to a DAC when the clock should be where it belongs, inside the DAC beside the DAC chip if there is such a chip; not through a cable in a different box. This is so idiotic, it's not even funny. It's a money grab." If you need a translation, Meitner in essence says that external clocks are for synchronizing multiple digital workstations for audio/video editing work. They're not meant to improve the performance of single devices as audiophiles practice to the tune of up to €35K for an Esoteric rubidium clock. It's back to the same argument COS make. The best clock is inside where it connects with a few centimeters of circuit trace, not through a digital cable with two connectors in a different box.

New LHY of my LAN. In the aftermath of a multi-stage review assignment for LHY's SW-6 and SW-10 switches plus their matching OCK-2 masterclock, I permanently adding the smaller SW-6 to my existing SW-8 as shown next. Whilst getting laid on the LAN, I learnt a few things. 1/ replacing our 20m CAT8a copper spur with fibre (SW-10 within 50cm from the router) then running that straight into the SW-6 and out from there via special RJ45 isolated by extra transformer IC was as effective as running the two shown switches in series with SOtM's inline isolators. Because I already had the SW-8, I decided against the fibre route. 2/ syncing the SW-10 and SW-6 switches to LHY's masterclock made no difference I could hear. 3/ using the same masterclock on my desktop instead to sync a Singxer SU-2 USB bridge and iFi Pro iDSD Signature DAC improved ambient recovery and treble sweetness enough to buy the clock.

Given that I now had my own LAN distributor with optical port…

… I asked COS. Did they want me to review their S-10 off that? I'd simply change the earlier sequence to CAT7 copper into the SW-6's isolated RJ45, out via fibre into their S-10, then out of that via my usual final 1m CAT8a into the iMac's network card.

All I'd need from COS would be two optical cartridges and a 1m stretch of fibre. Certainly that was easier than sending me another D10?

"Yes please." This was followed by more R&D insights.

"We're still tweaking the D10's optical module. We tested it in the showrooms of three local dealers. They all love it. However, in one system we found that unplugging the fibre could change the sound to some degree. That's to say that the performance was somehow inconsistent. We can't reproduce it in our own system and the dealer's audition space is constantly busy so we only manage a few hours there each Monday.

"It turns out that we had noise remnants inside the D10 which the fibre-optic module somehow amplified. We've already changed the AC inlet and digital/analog ground connections but aren't quite satisfied yet. It might read bizarre but we've narrowed down the culprit to our USB port. If a cable sits in it, the sound is wonderful regardless of whether the fibre plugs in or not. So this USB connector doesn't like to be left open.

"Engineering wise that's obviously not a graceful situation so we're still working on it but are very close. Since the other modifications already improved the sound regardless of input source, this troubleshooting certainly wasn't wasted."

When my small hold-thee-over COS box arrived, it contained two SFP modules marked 100Base SFP1G-SX-85 from Shenzen's fs.com; and a super-skinny 1m single-lead yellow Plus Corning SMF-28 Ultra fibre-optic wire.

These names are Swahili to me but networking nerds might enjoy having them?