Why not?

@bruce19 Forgot to write that once I had Krell Evo 302 amp and got the power cord with it as well. It was 20A thick wire and it almost looked like ordinary 'black' cable that you get with other gear (only much thicker and surface was smooth, like insulation on Cardas cables) but it was 'better' sounding than few that I tryed on its place. Could I perhaps find a 'better' one? Perhaps, but, imho, it takes lots of time and lots of cables to find the one you consider the 'best' (even if you have the idea what 'type' of the cable or the 'sound' you are looking for).So, sometimes if some piece of gear plays great already with its power cord (like that Krelll, finding the aftermarket cord is something that I worry less about) Imho, the power cord on any component must be in synergy not only with that piece of gear, but with the rest of the system, including all wires.For example, sometimes is possible to find 'better' cable (per se) for some component, but some other might be better suiting for the sound of the whole system

Wouldn’t they be in the best position to test or design the optimum cable for their component?

Yes and no. They could pick the best PC that works IN THEIR SYSTEM, but that’s in no way a guarantee that it would synergize best with a customer’s specific needs. Given how cables can sound different in different systems and the quality of power, power conditioners, etc. varies greatly in every system there’s really no “one size fits all” solution for cables and why 95% of all manufacturers don’t include PCs or interconnects with their equipment. If the cable qualities were consistently translatable they’d include or at least offer them. Making cables optional is a thought, especially if they can be offered at a discount, but most seasoned audiophiles won’t do that as they know what cables work best in their systems and will in all likelihood stick with those. Obviously including any quality cables would jack the price up of any component dramatically after retail markups and make them look much less competitive compared to those that just provide a passable cord and let the customer decide where to go from there. If it made sense to offer better cables with their gear manufacturers would be doing it, but they clearly know it’s to their disadvantage to do so unless they’re in the cost-no-object category where they can bury the cables in the astronomical cost of the equipment.

Audio Note looks like a very cool company although I am sad to say I have never heard their equipment. Just the fact that they offer a DIY line puts them in another league (for the better IMHO).

I was actually aware of PS Audio and Audioquest. I bought a couple of power cords when buying a power conditioner from them on the strong advice of the sales person but I must admit I just use them because I have them now. It seemed to be a co-marketing arrangement as much as a clear endorsement. The aggravating fact is the lack of clear statements, much less data to help sort the wheat from the chaff. It seems like this cable searching business could take a lifetime and the cable sellers are not unhappy with that situation at all, much as Nonoise suggested above! I guess I'm looking to identify those manufacturers who have the courage to step forward and say something definitive with regard to how their products are connected. So, I am grateful to those of you adding to that knowledge base.

Making cables optional is a thought, especially if they can be offered at a discount,

@soix you raise an excellent point which I forgot to mention. Certainly if one or more cable models where determined to give top results the manufacturer could negotiate bulk purchase pricing to help make an attractive package deal.

My concern is that manufacturers don't speak on this issue because they don't want to stir up a hornets nest among their industry brethren. A reasonable supposition that leaves us consumers out in the cold.

Audio companies don't want to increase prices of their units with 'better cables' that may or may not work with their systems. So, they leave it to owners to decide what they like/want.

That is the reason.

(And, yes, I asked them).

B