i can highly recommend a Tube Preamp like Audible Illusions L3A and either a solid state or Tube Amp. i used a ARC VT-50 with mine. class A pre-amps with separate power supplies coupled with a separate tube amp produces a very engaging listen. having said that a good solid state integrated with a class A pre-amp section with a separate power supply for each section would also be a good listen. i find the most engaging sound is a product of good timing. timing is a big deal. also power supplies make a huge difference. you may also consider dedicated A/C lines running into you listening room. any qualified electrician can handle this. i use separate. one line for the front end and a separate dedicate line for the amplifiers. clean power makes a noticeable difference. btw, your Harbeths are very good. keep them.