Thanks all for comments and suggestions!
A few questions/clarifications and apologies in advance for being slow;
I should perhaps clarify that I have chosen Sonos as my multiroom system so everything needs to be connected to Sonos at some point in the chain...
No one is recommending the Beocenter 9300 for the amp function - why? I thought the 9000-series was the original partner for the Beovox Pentas?
ICEPower is the best way to go?
Option 1 then would to go with the Beoamp2 which gets me 2x125w icepower but then I would need a receiver to control volume/tone etc to connect to Sonos port.
Sonos Port - eg BS3000 - Beoamp2 - Pentas
There is a used Beoamp2 on ebay for EUR 480, a BS3000 I can pick up for EUR 250 so total cost incl. Sonos Port comes to EUR 1.180
Option 2 is basically the same except switching out the Beoamp 2 for a Ghent Audio option
Their 2x125w version costs EUR 930 so total cost incl. Sonos Port comes to EUR 1.630
Option 3 would be to just use the Sonos Amp which would give me 2x125w but no icepower. Cost EUR 800
Option 4 which no one seems to like is the Beocenter 9300 which would give me 2x80w no icepower
Sonos Port - Beocenter 9300 - Pentas
Cost would be EUR 250 for the 9300 and 450 for the Port so total EUR 700
None of the above take into account import duties (ghent is chinese?) cables or installation costs.
Further questions;
How much flexibility do i have in terms of placement when running cables from the amps to the speaker and then from amps to receiver? I.e will i lose sound quality by running long cables?
Can I use a beocenter 9300 in the beoamp2/ghent set up? I.e only use the 9300 as a receiver and bypassing the built in amp?
Am I correct that the Beolab Pentas had 150 and 200w amplifiers depending on version?
Are the D-class amplifiers in general and ICEPower amps in particular, more capable at the same watt spec?
Am i getting the options right and if so, which options makes most sense?