Components on floor

You should be ok as long as you use some type of isolation under each unit. Springs much preferred or at the very least soborthane. No spikes! Anything place directly on the floor, regardless of floor material, will be an invitation for unwanted vibrations.

It shouldn't cause any negative problems.  The installation method of your floor will determine exactly how prone it is to external vibration, but its mass is quite high compared to shelves or racks.  It would take high amounts of energy to get the floor moving.

nothing to worry about outside of tripping over wires if not managed well

Wall mounted electric fireplace? What is that... does it have motors and re-stats? It might create some interference...

I agree that isolation would be necessary. Springs at least. The floor is seismically active and will transmit the truck and car traffic, actual seismic activity. I have a seismometer in my house. It is surprising the difference in background vibration between day and night. This is why Townshend Seismic platforms (under speakers) are so effective... but also important for components. 

 Is this a bad idea, and if so, why?

Yes.  You have to bend over to use them.  Must you put them there?

Do you mean that the hardwood is directly attached to the concrete (ie: glued?)  My components sit on the concrete slab under my house, si the result should be similar. A 10,000# slab is pretty stable so there's no problems with vibration, though I  understand that surface waves can travel on top of the concrete but that's obsessive, even by my standards. Wire dressing is no more of an issues than with a stand. Bending down at my age IS an issue. The preamp and streamer are both remote equipped but the turntable is a pain! I've considered a sand filled concrete pylon to put the table at chest height but have not yet done so. Dust needs vacuuming daily. A unexpectedly significant improvement comes from not having anything sound reflective behind and between the speakers, which is where my components sit. It's like gaining an extra foot of wall to speaker distance. Overall, I love it!

You should be fine.  I have a floating wood floor and I have a lot of issues with vibration.  We have an extra bedroom in the basement with a cement floor and there’s absolutely no issues.  

I have mine on finished plywood which sit on short legs. Each component sits on anti-vibration pads. Only issue is the dog likes to lean on the plywood!

No issues. I had amps on the floor. Much better sound than having it all in a rack. Spread the components out and you’ll be fine. If they are at least 1 foot away from the fireplace you’re good. However if they are on the same circuit as the fireplace you might get some AC line noise. See how it all sounds. 
 

I have all source components on a DIY decoupling shelf system. I have suspended floors. My subs sit on Stillpoints SS, my monos sit on a Symposium Ultra each with HRS footers. This does a great job. I agree that a spring setup under wood platform would be A very effective solution.

I’m thinking of about a Dimplex IgniteXL 60" fireplace unit that’s either on or off.  Instead of mounting it to the wall, the carpenters will build a cabinet to hold the unit at the top with a shelf at the bottom for audio gear.  The cabinet will abut the wall behind with slots for ventilation.  The floor is hardwood over concrete.  The walls are furred-out studs and wall board over concrete.  The gear is an Ayre DX-5/20 disc player, QX-5/20 DAC/preamp, AX-5/20 integrated amp, and Roon Nucleus.  I gave my Thorens TD124 and vinyl to my cousin.

I’m 89 but can comfortably bend to insert a disc.  Mostly I stream music or watch YouTube/Netflix on the 85" Sony. 

Don't put them on the floor. Use amp stands.

I’d say lord in heaven no if not a concrete floor.  Even so elevating a bit makes use easier.  If foundation level and any chance of flooding,  definitely no. Distance from any nearby electric devices always desirable just in case. 

OP

just isolate the hard wood from the concreate floor. It should work

Get some butcher block boards that fit under each component, under the blocks put your favorite footer. 

@dbphd 

I agree with @ghdprentice, I would avoid placing sensitive equipment close to the electric fireplace. Besides heating elements, the fireplace contains fans, LEDs to illuminate the faux flames, and all sorts of control circuitry. Lots of opportunity for undesirable electrical noise.

Users manual here https://www.dimplexstore.com/dimplex-ignitexl-60-inch-linear-electric-fireplace

Two words: vacuum.cleaner. 

Also, do you like standing on your head to adjust the volume? 

Can someone please explain the supposed advantages of putting your equipment on the floor?

@panzrwagn 

One advantage is that you don't need to spend $15,999 on an Audiophile rack 😃

@devinplombier I could pull an 'Audiophile Rack' in for $9,999, easy. 

There's many variations of "wood-faced concrete floor".

Is the concrete a slab on the ground or a suspended slab?

Is the wooden floor freely floating over the concrete or firmly attached?

My partner's place has a concrete slab on the ground, to which solid hardwood planks have been attached.  The planks are Australian hardwood - red ironbark to be precise. This stuff sinks in water and can be machined like metal billets!

The installers lined the floor with a waterproof membrane then fixed thick plywood sheets using explosive nails, Each hardwood plank interlocks to the next, and was glued and edge stapled to the plywood.  The whole thing is about as rigid as you could get.

Mostly, Australians use floating flooring using manufactured sheets of mdf with a thin veneer.  The sheets interlock and sit on a foam or rubber underlay.  There is no positive mechanical attachment anywhere and gaps are left at the walls to allow the floor to expand and contract.  The floor bounces by design.  That's what my partner used to have.

Thanks to devinplombier directing me to the Dimplex users manual, I decided to recess the fireplace near the floor and mount the audio gear in a separate rack.  The Ayre DX-5 DSD will be waist high for easy disc handling, and the all the gear is controlled by remotes.