There are two questions to answer before you proceed any further.
First, are you also unhapy with the sound quality if you are listening to Tidal through the Sonos Connect? If yes, you are probably unhappy about the sound of the speakers and/or the room. If not, the sound quality problem is in the audio quality of the TV signal or in your external DAC. Do not overestimate the quality of the signal that is used in tv broadcasts or by cable companies. It is often sacrificed to save on bandwith. If that is the case, there is nothing you can do. As for the DAC, if you are using an ultra cheap external DAC there could be an issue, but otherwise not really. Did you try the analogue output of the TV (if it has any)? Some DACs built into the TVs of major brands can be quite a bit better than cheap external ones (the DAC in my Panasonic Plasma certainly is fine).
Second, do you plan to go for multichannel HT or just stereo HT? Personally, I have opted for stereo HT with a very good stereo system with large speakers (Quad 2805 with B&W PV1d sub and Antimode 8033). My priority is music, and I cannot imagine having five or even seven huge electrostats in my living room. The result is really very good, and on balance far better than I could get for the same budget and space requirement spread over five main speakers. Stereo HT does not need any special processor. If you want to watch Netflix all you need is to add a Chromecast, and if you want to play (UHD) Bluray, just add a player like the Oppo 205 that can serve as a pre amplifier as well (make sure you buy one with stereo outputs). You can use a digital output of the Sonos as input into the Oppo.
First, are you also unhapy with the sound quality if you are listening to Tidal through the Sonos Connect? If yes, you are probably unhappy about the sound of the speakers and/or the room. If not, the sound quality problem is in the audio quality of the TV signal or in your external DAC. Do not overestimate the quality of the signal that is used in tv broadcasts or by cable companies. It is often sacrificed to save on bandwith. If that is the case, there is nothing you can do. As for the DAC, if you are using an ultra cheap external DAC there could be an issue, but otherwise not really. Did you try the analogue output of the TV (if it has any)? Some DACs built into the TVs of major brands can be quite a bit better than cheap external ones (the DAC in my Panasonic Plasma certainly is fine).
Second, do you plan to go for multichannel HT or just stereo HT? Personally, I have opted for stereo HT with a very good stereo system with large speakers (Quad 2805 with B&W PV1d sub and Antimode 8033). My priority is music, and I cannot imagine having five or even seven huge electrostats in my living room. The result is really very good, and on balance far better than I could get for the same budget and space requirement spread over five main speakers. Stereo HT does not need any special processor. If you want to watch Netflix all you need is to add a Chromecast, and if you want to play (UHD) Bluray, just add a player like the Oppo 205 that can serve as a pre amplifier as well (make sure you buy one with stereo outputs). You can use a digital output of the Sonos as input into the Oppo.