How do you feel about a wheeled dolly permanently under large floorstanding speakers?

caper, yes, absolutely, casters on the bottom of the speakers in place of the spikes. It works beautifully!

Note, it will probably yield a superior result to spikes; as I said, the (often) additional elevation of the soundstage is considered by the ear to be advantageous. You don’t even need locking casters - unless you have a downhill slope to your floor! ;)

Here’s another reason to consider casters; you can probably alter the front baffle slope to improve the speaker. The Vapor Audio Joule White speakers I have do not have perfectly even height of the casters - I intentionally altered their height. The rear casters have two additional washers, which lift the rear of the speaker slightly, adding a hair more forward baffle slope, and imo give the speaker even better sound. Of course, it’s completely adjustable, as one can add or remove washers to suit. Imo, that is a far more important adjustment than whether the speaker sits on a spike or on casters.

With casters you can quickly, efficiently, check whatever placement you wish, and I encourage you to not waste time. You do not need days or weeks to move the speakers to your preferred location. Move them several times in a day if you wish. You will dial in a much preferred result quickly. There is no advantage to wasting your life on it. If you want, change it back, etc. Take a piece of tape and make a mark or two for preferred locations. It’s simple.

Absolutely, use a lock washer for the caster to cinch down. Select a robust caster, and don’t be chintzy about it. On wood floors be careful, as the weight of the speaker on the caster as it moves can put a running compression line in the wood! You do not want a thin wheeled caster, but one with more width to distribute the pressure so you won’t get damage. Note casters that can handle higher weight, and still have width to be ok on delicate floors. There, I just saved your flooring. :)

Herbie’s are great, work very well with lots of options for just about any setup.

With regard to ozzy62’s comments concerning maintaining precise placement (to 1/4 inch!)... I always wonder when I read such advice - how does one maintain, let alone reproduce such precise head positioning? 

I do exactly as you describe, wheels to the rescue.

my speakers are quite heavy, but 60-80 lbs is a lot, heavy enough for wheels IMO. Go to Home Depot, pick up an 80 lb bag of concrete, walk the length of the aisle. Put it on the floor, try to push it with your foot. I’ve done spikes/wheels, nothing lost by wheels, much flexibility gained.

the advantages of easy toe-in modification for two listeners important as well as ’parking’ them. Luckily I have a wood floor with a grid, alternate symmetrical location marks easy.

3 wheels (2 front, 1 rear center), always avoids wobble, more weight per wheel than 4. (more below). Not swivels, too much easy movement, you can slip/slide sideways as straight rolling wheels slowly roll forward.

four alternate positions

a. ideal for listening, out, away from rear and side walls, toed in to pre-defined angle,
b. toed in further when/for two chairs and a small center table. either chair closer to one speaker but other speaker aimed more directly, volumes equal enough to preserve imaging for two.
c. half way ’back’ lower volume listening, more room to get around.
d. fully ’parked’ in the corners when needed/desired, in your case also WAF.
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rear ’slightly short’ corner blocks, to prevent tipping.

3 wheels is unstable, I put two rear corner blocks, 1/4" shorter than the rear center wheel. any tip is ’caught’ quickly by the corner block, but when in position the blocks do not touch the floor.

therefore a rectangular dolly can be modified, move one of it’s rear wheels to the center, and add some ’slightly short’ rear corner blocks/

a triangular dolly will have no place to attach corner blocks, so you need to attach a rectangular platform to the top of the triangular dolly.
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skirt

a skirt around the rolling platform can be built to conceal the wheels.
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tilt speakers back slightly?

Add a block above the two front wheels to raise the speaker’s front up (situation varies of course). After forward location and toe-in is essentially solved, listen, then try a temporary block,

a. time alignment of drivers (highs travel faster than lows) (also WAF involved)
b. aim tweeter’s narrower sound waves directly to ear height of listening position
c. non-parallel initial and reflected sound waves to floor, ceiling, and reflections off rear wall will be more diffuse. toe-in avoids this for side walls.

Mine: a matching wood skirt, 3 permanent wheels, rear anti-tilt corner blocks, and front lift.

Wheels: mine: enough surface to avoid marking the wood floor, but the smaller the contact surface, the more weight/contact area, and
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office chairs, professionally ordered, offer two types of casters:

hard wheels on carpet/soft surfaces. slightly soft surface wheel on hard floor material.

Note: you don’t need to get perfect wheels to get started if you set it up to change them later if you find something preferable.

Mine are permanent, but it is easy to arrange a non-permanent trial or easily removed solution. I could remove my skirt and wheels, I cannot imagine wanting to.