Have you ever used a separate speaker selector unit to audition speakers? Would you?

@b_limo Thanks for giving a reason and not just an opinion.
@tablejockey I've been instructed not to turn tube amps off and then immediately back on but to give them a couple minutes. Folks have reported burning out rectifiers doing this.

Look, no one would put a switch box in the signal path for no reason. But if you need to compare gear it’s a much better way than powering up and down and swapping cables.

This is the only reason I would put a switch box in -- to try to make a comparison. Then, I’d set it aside. Regarding @b_limo point about variables — the idea would be to use the same cable and keep the other elements as similar as possible (positioning, room, etc.) It might be necessary to quickly move the speaker being auditioned around a bit — but that can be quickly done, compared to the amp on and off rigamarole.

Of course, if the switch box isn’t high quality, then I could be degrading the sound too much for both speakers and erasing important details which would be crucial to their character — and their difference.

It seems this is another debate that rests upon empirical details not fully definite -- which speakers, which switch box, etc. I don't have the speakers yet, so this is impossible to detail, yet. I'm trying to decide on buying a switch box.

Another option is for me to get a switch box and try both. If I hear no degradation of sound with the switch box on either speaker, I can go ahead and compare them.

@david_ten and @catdoorman - I was thinking I'd just pop one set off the stands, put them on the floor, and put set #2 on the stands in their place. Exact same placement for the comparison. Perhaps different speakers need different placements -- granted. In that case, I'd have a second set of stands ready to go.

@miller My effort to find a way to do careful and detailed analyses of complex phenomena does not stem from my inability to "think it through." Rather than imply I'm being obtuse, you could either just report that *you* never needed to do or perhaps suggest ways that you compare things.

Ask yourself, if you really can't remember, then why would you care? If you have no memory of something better, how can anything be worse? Seriously. Think it through. Why would you care?

Yes, one possibility here is that I'm just stupid. But another is that you tend to rush through experiences or don't pay enough attention to realize they are complex. To a gourmand, all food can be gobbled up quickly. But I've read other comments you've made in other places and know that you are a careful listener. Why not draw on that experience and contribute something you've learned to this topic rather than finding a way to demean the question -- and the questioner? 

@david_ten Thanks. I get it more, now. I'll establish placement for each speaker, mark it, and make sure that nothing extraneous gets in the way.

There are all kinds of obstacles to a perfect comparison -- how long it takes to get used to things, burn in, placement, etc. Either those obstacles are great enough to indicate no point in comparing or they're minor enough so that there is something to be learned by comparing.

I'm going to assume there's something to be learned and do the best I can. (I also think this will be a pleasurable experience.)

If I hear no difference, I choose on other factors. But whatever happens, I'm the sort of person who wants to go through a process before making a final decision, even if that process will be less than ideal.

@miller Thank you for this answer. I have a better sense now of why you made your first comment, and perhaps I let my feathers get ruffled too easily.

The cumulative voices against the switch are mounting, and I didn't intend for it to *replace* deep and patient listening; I meant for it to be an *additional* avenue of comparison. Wanted to make that clear. 

One detail of your story reminded me of my initial cause for posting:

 I had driven 200 miles. Okay I will try without the magic switch. Listened a few minutes to their wire. Okay, pause, put mine in. Instantly, and I mean so fast I hadn't time to sit down, it sounded like I broke the guys expensive tube amp. I could hardly believe. My wife was there too and she could hardly believe it herself.

Because I don't want to damage my tube amps, I don't have a chance to do what was part of your own story -- the fast switch, "so fast I hadn't had time to sit down." I'm not going to do that with my amp, so I have to hope that switching slowly is sufficient to hear all the differences I need to hear. And you -- and others -- have attested to that. So, that's what I'll do.

@teo_audio Thanks for this sensible comment, which echoes others:

If you find that you can’t tell the differences between the two, unless you had a switcher for instantaneous switching, then they are close sounding to one another.... close enough that it’s in the ’six of one, half dozen of the other’ kind of category.

I have more or less accepted the answer that "quick switching" is not the way to go.
By accident, I heard this said this morning by Hans Beekhuyzen — don't switch quickly to evaluate speakers.
https://youtu.be/idxT7VVYyxo?t=523 

@dbphd Is this what you mean? https://sites.google.com/view/pine-tree-audio/devices/transparent-selector

Thanks, @jetter  I do think you're right -- it's another tool to use. I guess what I've learned is that it's not to be considered a primary tool. 
That said, I have read some interesting things about the ephemerality of aural memory from sources which are bona fide scientific and rigorous. It's not just me, questioning what I just heard. It's well-documented that aural memory is subject to many physical and mental sources of error.

@ebm I think we’re agreed on that.

@twoleftears 
I think it does level the playing field. However, what I take is being asserted as common wisdom means that is not so important.

This is what I gather the common wisdom is:

(a) speaker selectors degrade the sound. The question becomes "how much"? If they don't degrade either too much, then there is something to be learned by using the selector as *one factor.* (We have all compared this way, and I know from my experience that I heard some differences of a general kind worth heeding.)

(b) longer term listening is the primary way to make the comparative judgment. This kind of critical listening takes practice and patience and should not be sidelined by the urge to switch quickly.

(c) longer term listening renders sufficiently solid judgments that it makes what can be learned by quick switching negligible.

@miller Hearing your comment as not snarky. Thank you.
I had supposed that if I narrowed speakers down to fairly similar types, the quick switch would be one additional tool to help make some distinctions.

I thought in the past that I had gained *something* by switching, but I would be willing to stipulate that I was not really learning what I thought I was learning. I may learn something by supposing I was mistaken.

You are saying that there is absolutely nothing to gain by using this kind of comparison.

The only question left, it seems, is for anyone else reading this thread, still: Did YOU learn anything by quick switching? 

@rrcpa I'm convinced. 

@aburn Well, that is one key point of contention, and you can see I've pointed to it a couple times in previous posts. You can also see different arguments for and against the usefulness of the proposal. Rather than rehash that material, I would just suggest reading the thread from the beginning.

@br3098 You succinctly captured what I thought was the argument for the selector as one point of comparison. I’m still curious to try it, though I see better why it might not help much.

One line of argument against it has to do with whether or not fast judgments are helpful. Some here argue they’re not. You say they can be (and this was my experience, too, but I’m questioning it).

But another line of argument against it has to do with the effect of the selector box on the speakers.

Just for the sake of argument, I can imagine a scenario where it doesn’t help or even hurts.

Consider a comparison between Speaker brand A and brand B using a selector.
In this example, imagine that Speaker A is greatly affected (obscured, masked, distorted) by the selector electronics but Speaker B is not. Voilà! What seems like a neutral test is actually making the comparison worse. The assumption was that the selector would affect each speaker the same amount, but that was a wrong assumption. (Imagine feeding the same amount of sugar to a diabetic and a non-diabetic. Should have the same effect, right? No, it shouldn’t because they start from different positions.)

It sounds like you have a lot of experience selling speakers over the years. Is the example I am offering here far-fetched? Happy to be corrected if so, but it seems plausible in theory.