Time for a Pre change? Need the wisdom...

I have Mac 601 monoblocks with a C-2300 tube preamp driving Sonus Faber Guarneri Evolutions.  All high end SR cabling.  In a search for "detail" I went to the Rollerblock isolation technology and my system got so bright it was almost unlistenable.   Quite a feat when you consider those components as none are considered bright, in fact the opposite.  What I discovered was all the detail especially in the HF range was overpowering my room.  With lots of research and the help of GIK Acoustics we treated side wall 1rst & 2nd reflection points with absorption as well as immediately behind listening position.  We used difusion on front and back walls as well.  Results are incredible...soundstage off the charts with lots of detail but no harshness or glare.....very musical.  I have a few pictures on virtual systems.  You might give your room treatments a closer look.
Happy listening!

Duelund speaker wire is very good and affordable. For a 10 foot pair either 16 gauge ($120) or 12 gauge ($240) from Parts Conexion. Look up user grannyring or Acoustic BBQ if you want a premade pair. It probably won't hang with a $$$$ set of wires but can compete against anything <$1k, some may sayer higher.

I agree with @treebeard1.  I use the duelund, made my own pair and it was super easy and a great investment.  For some details see this link (with more links included).  A number of threads around here to...

http://www.hifihaven.org/index.php?threads/more-duelund-fun-this-time-speaker-cable.3156/

Get the ARC Ref 10 linestage preamp or the Ref 6 if you can't swing for the Ref 10.

The 10T's aren't a harsh speaker, but electronics can certainly cause any speaker to sound poor.  The 10T's are one of the most listenable speaker that I've heard and I've lived with them for about 10 years.

They do need a quality electronics, especially the amp, to sound their best.  I'm not a fan of Mac and own JC1's so I'm probably biased but I think you will find that your 10T's become much more enjoyable with the A21/P6 combo.  Don't listen to the JC1's unless you're ready to buy a pair, they are a perfect match for the 10T's.