Switch from AB to D

@vinylrecord61, I purchased 2 different class D power amplifiers and, in my opinion, NEITHER Class D amplifier was ready for prime time. I was not happy with the way they sounded, they were not musical and I eventually took the loss and sold them. As per many other Audiogon posts, it seems, everyone has an opinion about the sound quality of class D amplifiers. For me, class D amplifiers do NOT have the sound I was looking for at ANY price level. I give Class D amplifiers a F (my opinion) at any price range. I am sure that other people will disagree with me and that is okay. Everyone has a different opinion when it come to audio equipment and what sounds great.

I eventually purchased a SimAudio 700i V2 integrated amplifier and like it very much. Based on my experience, I suggest you audition some class D amplifiers and also some other class A/B amplifiers. I also own the SimAudio 340i amplifier and it is excellent. Please continue your research into class D vs. Class AB amplifiers.

Several retailers will offer you a home demo so you can listen to the amplifier in your system and then make your decision. The more important thing is maybe you NEED to find an excellent retailer (local, if possible) for advice and consult with them on what amplifier you should purchase. Based on your above comments, I strongly suggest a home demo is your best option to help you make a decision. Please remember it is your system, your environment, your budget, your other equipment and listening that decides what to purchase. It is not an easy process.

Please take your time and do not rush the process. I hope this helps.

@mr_m,  As you requested, I owned the Hypex NCore NC400 Class D Power Amplifier dual-mono blocks (2 NC400's per box) and the Mola-Mola Kaluga NC1200 Class D Power Amplifiers.

Based on my listening experience, with both the Hypex Class D amps and then the Mola Mola amps, I did not feel they sounded very musical in my system and environment.   In other words, they did not sound natural and I had problems listening for long periods of time.
  
I asked several 'experienced' audio friends over for a listen and they agreed with my thinking.   As I said in my above post, this is MY opinion and others may disagree.   In fact, based on other Audiogon posts, I know that some people like Class D amplifiers.  I do not like Class D amplifiers based on my listening experience with theses amplifiers.   I hope this helps.  

I then purchased the SimAudio 700i V2 integrated amplifier.  My SimAudio 700i V2 amp sounds excellent. It sounds clearer with more musical detail, better bass and more.  The sound quality of the SimAudio 700i amp was exactly what I was looking for.   

@vinylrecord61, You received 27 suggestions recommending Class A/B, Class D and class A.   In addition, you received specific recommendations for various brands of amplifiers (excellent information).   Most every post I saw highly recommended something and was very useful.

Your original question was "what am I going to experience putting a Class D amp with a hundred watts per Channel in place of my Onkyo with 140 watts per Channel at class A B power?an easy process?”.   Based on these 27 posts, I do not know if we actually answered your question.  I will say you received many useful and different opinions.

Since you are unable to visit your local retailer, I suggest you contact a retailer (local, if possible) that will loan you two amplifiers, class D and Class A/B, for you to demo in your listening room.
  
Please remember it is your system, your environment, your budget, your other equipment and listening that decides what to purchase. It is not an easy process.   Please keep us posted.