Worth upgrading my cables?

@mceljo 

Well new tubes - different sound. Just like in a solid-state amplifier, the main filter capacitors, power transformer(s), and small changes the circuit design can vastly improve or detract from sound quality, or objectively accurate audio playback.

Sounds like you've spent a lot of time comparing the inerconnects/cables. Maybe the difference is related to better shielding from RF noise, superior conductors, and better (less grain) crystal structure of the wire in the cables...which can make for a technically superior conductor. I won't say all cables are the same. Actually, far from it. For this reason, I have custom interconnects and the brand of choice is REAN. 

Over the years I've used throwaway cables...strangely always noticed a slight warmth in the midrange that shouldn't be there on certain tracks. For instance, when Diana Krall sings Black Crow - there is a unique peakiness in her voice that seems to defy the laws of dynamic range. It's so wonderful. 

Happy listening!

Lots of good comments already.

Before I'd shell out serious money for any cables, depending on length, less than $200 or so, order some custom length Blue Jeans cables. 

www.bluejeanscable.com

In my own A-B testing with high quality rolls of 12 gauge wire, the very pricey Rocket 22 AudioQuest, and Blue Jeans, the difference between AudioQ and Blue Jean Cables was imperceptible. Additionally, AudioQ terminations are twisted bare wire and set screws (really?!) to whatever you choose (banana or spade). Oh, and BTW, AudioQuest silver "SureGrip" bullet sleeves are so fragile, you will bend  and break them by simply lifting or adjusting your wires. No problem since you can buy replacement ends "SureGrip" silver 300 banana connectors for a mere $60.00 for 4 if you can find them. They are anything but "SureGrip" more like, "surely to break." 

Blue Jeans offers 14, 12, & 10 AWG and ultrasonic weld that seems to be a significantly better connection. I was very impressed with the workmanship, quality, and fit of the welded ends. They offer more options for connections and at no extra charge, you can choose different connections on each end (locking bananas, 2 different sizes of spades, BFA, and 3 different fork terminals, or unterminated). They also make most other cables (HDMI, Subwoofer, Data, SDI, and adapters...) I've been extremely happy with Blue Jeans in two different rooms (in one room running bi-amp wires, the other just two-conductor cables). 

I noted one person recommending Morrow Cables. I looked long and hard at their products - even inquired in these forums - but the "fact" that they are always 40% off was curious. Not to mention their incessant email advertising. (Give it a rest, Morrow.) If a cable is that great, why are advertised prices so high that they offer perennial discounts? Are they so overpriced they are always on sale? Makes me wonder who got suckered and paid full retail since they are always on sale. Just an observation. They might be great.

And pertaining to power cables, as other posts have noted, hire an an electrician to install a dedicated power line to your audio components is the best cable money I've spent. (My electrician laughed at first until he crawled under the home - fortunately we have crawl space that you can stand up in - that there were no less than 14 outlets off the main to my room. He tested before and after and the draw was amazing. So for less than $300.00 I have a dedicated line and sliver plated outlet installed. I was shocked at the difference. As I've told several of my audiophile friends, it was the most significant improvement in my system. Depending on access (crawl space or attic access), it may be helpful for you. 

Happy listening! 

@dreas - I have have Blue Jeans Cable 10AWG speaker cables and have been very happy with them. Like you, I really like the ultrasonic welded connections.  I have not compared them anything “high end” but they seem to do pretty well. 
 

I had BJC LC-1 interconnects and found Audioquest Chicago to be better in my system. It wasn’t a subtle difference and given the price difference I’d go with AQ over BJC for unbalanced interconnects. 
 

I now have a Morrow Audio balanced interconnect and am very happy with them. Their marketing definitely is annoying. I emailed them to poke at it a bit. It’s a very intentional strategy that’s working for them. In short, people like sales so that’s the approach they have taken.  A little too much like Wilsons Leather!

Zavfino cables and Grover Huffman cables are both superb performers.

@designtaylor
your last post was spot on- the entire audio chain matters so it’s usually best to address the weak links.