Installing full vinyl on adhesive vinyl - is impact sound insulation necessary?

First of all, hello to the forum.

I bought a house built in 2016 where glued vinyl is installed in the basement. Since I would like to have a different vinyl installed, the question arises whether I can simply lay a 4.5 mm full vinyl over it.
There is underfloor heating.

What do I need to consider?
Another impact sound insulation underneath?
Will the thermal resistance be too high?

I called a vinyl supplier who said I should at least lay a vapor barrier underneath. But I had the feeling that the seller was slightly unsure.

Or should I rather tear out the glued vinyl? I would like to save myself the work.

I found nothing on the internet about this topic.

I bought a house built in 2016 where glued vinyl is installed in the basement. Since I would like to have a different vinyl installed, I ask myself whether I can simply lay a 4.5 mm solid vinyl over it.
Underfloor heating present.

What do I have to consider?
Another impact sound insulation underneath?

There is no impact sound insulation under the glued vinyl.

Yes, you need impact sound insulation. The build-up height is then at least 6 mm. Does that still fit with doors, doormat under the front door, etc.? A vapor barrier is not necessary because the floor is already sealed.

Warning, I am a layman.

Will the thermal resistance become too high?

How high is too high?
If you pay attention to low thermal resistance with the new covering and impact sound insulation, it basically works. The value remains better than with laminate, but of course worse.

Thermal resistance before: <0.02
Afterwards: 0.045 (0.02 + 0.02 + 0.004) in the absolute best case including impact sound insulation. Depending on the covering, however, it can also be significantly higher.

A thermal resistance of up to 0.15 is considered OK for underfloor heating. I don’t know who defined the 0.15.

In the worst case, you have to increase the supply temperature of the heating because otherwise it will not get warm. Especially with heat pumps, that costs efficiency. Possibly you have to raise the temperature of the floor beyond the manufacturer’s specifications.