Though in a very compact form, you won't do much better than this for that modest amount of money -
SMSL AS18 -
https://www.amazon.co.uk/AD18-Stereo-Amplifier-Bluetooth-Subwoofer/dp/B071JN7GXN/
Let's see if I can find that in Germany so we can see the price in EUROs -
https://www.amazon.de/SMSL-Verstärker-Bluetooth-Unterstützt-Lautsprecher/dp/B073RY78ZF/
That is more than you want to spend, but at under €100, you choices are really very slim.
SMSL makes quite a range of amps, so with significant power, but these are all tiny compact amps -
Shenzhen ShuangMuSanLin Electronic Co., Ltd.
The Power tends to be inflated, so figure the real power is about Half what they claim, but then ... how much power do you really need?
This ...as an example... is an immensely powerful amp ...for tiny compact amps. They claim 160w/ch, so you can probably count on a solid 70w/ch to 80w/ch.
(€117) -
https://www.amazon.fr/SA-98E-TDA7498E-Amplificateur-puissance-numérique/dp/B06X93PWR5/
Shenzhen ShuangMuSanLin Electronic Co., Ltd.
Checking
Amazon-FR and
Amazon-DE, the
Denon PMA520 and the
Pioneer SX20 while cheap in the UK, are about double your budget in Europe.
If you insist on that low budget, I suspect that the
SMSL and similar are about your only choice if you want a decent amp.
The
SMSL AS18 has lots of features, and a pretty solid 40w/ch -
DAC, USB, Bluetooth, AUX, Remote Control, etc.... A bit over budget, but seemingly a decent amp in a very compact size.
Shenzhen ShuangMuSanLin Electronic Co., Ltd.
This SMSL has a DAC as well as an Amp -
https://www.amazon.de/gp/product/B06X93PZ2W/
This SMSL has a Sub-Out if that matters to you -
https://www.amazon.de/gp/product/B079DLJJ3C/
These are about 20w/ch to 8 ohms, but for a modest system, that's fine.
The Lepia in the video driving the Wharfedale speakers is only about 10w/ch to 8 ohms -
https://www.amazon.de/LEPY-LP-2020A-Stereo-Verstärker-schwarz/dp/B012NR4SBE/
And it only costs a very modest €27.
At under €100 you choices are going to be limited ...unless... you want to start looking at USED equipment.
https://www.amazon.de/s/ref=nb_sb_noss_1?__mk_de_DE=ÅMÅŽÕÑ&url=search-alias=electronics&field-keywords=lepai+2020
To get prices in EURO's search AMAZON-FR or AMAZON-DE to get Euro price.
SMSL Amps -
https://www.amazon.de/s/ref=nb_sb_s...id=1VZ4G25UIP1Q6&rh=n:562066,k:smsl+amplifier
Lepai Amps -
https://www.amazon.de/s/ref=nb_sb_n...Lepai+amplifier&rh=n:562066,k:Lepai+amplifier
Topping Amps -
https://www.amazon.de/s/ref=nb_sb_n...ing+amplifier&rh=n:562066,k:Topping+amplifier
While these compact T-Amps are very nicely priced and sound good, they do have a limited number of inputs.
Steve/bluewizard