PA-28 Pilot reported they flew through a Class D airspace enroute to their destination after assuming the Tower was closed when they received no response to their radio calls. After landing they learned the Tower was not closed and had been responding to their calls.

Narrative

I departed ZZZ1 for ZZZ2 at approximately 2000 on date. I was flying VFR with a standard GPS as my equipment with 2 com ports. I flew south of ZZZ3 and directly over ZZZ4 en route to ZZZ at an altitude of 3500 ft. Once I had entered Bravo Airspace; I descended to 3000 ft. and prior to approaching ZZZ; I descended to 2500 ft. I have flown through Class Delta ZZZ airspace multiple times and I knew that the hours of operation were 0600 - 2200. I radioed the ZZZ Tower/CTAF at 10NM west of ZZZ with no response. I additionally requested a 'radio check.' I still had no answer/response. I attempted my 2nd com port and requested an additional 'radio check' along with stating my position prior to entering Class Delta ZZZ. Thinking that ZZZ Tower had closed early and ultimately; not seeing any traffic in the area or over the airport as it was still light at this time; I continued to utilize ZZZ XXX.X as 'ZZZ Traffic' to announce my position and my intention at 5NM; 3NM when flying directly over the airfield and through the ZZZ Class Delta airspace. I continued through Class Delta ZZZ and descended to 2000 ft. At 10NM away from ZZZ2; I requested a 'radio check' from ZZZ2 Tower. They stated that they heard me 'loud and clear.' I requested to land at ZZZ2 on Runway XX with information Lima. The ZZZ2 Tower gave me clearance to Runway XX with 'helicopter traffic to the west.' At this time I was speaking on our Com Port 2; the same Com Port with which I had attempted to make contact with ZZZ Tower and requested a 'radio check' with this Com Port after having no success with the Com Port 1 in the airplane. After landing and taxiing to the Flight Center; I was instructed to call ZZZ for possible flight deviation. I spoke with [ZZZ Tower personnel]. They stated that they could hear me; but I wasn't responding when they were communicating with me. I told them that I had attempted to communicate with ZZZ Tower on both of my Com Ports to no avail. I also told them that I would have our avionics guy look at this at the beginning of this coming week. After the call; I started the avionics in the aircraft and switched back to Com Port 1 again and I radioed to ZZZ2 Ground on XXX.XXX for a 'radio check.' ZZZ2 Ground stated that they heard me 'loud and clear' and I stated to them the 'radio check' request reason as ZZZ Tower could hear me; but I was unable to hear the responses. ZZZ2 Ground simply commented that it could have been a 'speaker volume error;' however; I never adjusted anything on either one of my Com Ports after making numerous calls and clearance while transitioning through ZZZ and ZZZ2 Tower - and ZZZ2 Ground; was able to hear my communications without issue.