About three weeks ago, I received my one and only SR Blue fuse to try in an Audio Research Reference 6 preamp. This new fuse would displace my SR Black fuse, should the system sound better with it. I swapped the Blue fuse orientation twice and settled on the position that provided the greater image focus. At that time, my first impression was that the Blue fuse tended to roll off the high frequencies. I decided to investigate more. The Blue fuse probably has about 60 hours of play time on it now.
To make a long story short, my judgement hasn't changed from my first impressions. The Blue fuse, in my system and to my ears, tends to roll off the high frequencies. With this change, the midrange tends to sound slightly richer. The bass does seem slightly more impactful and focused using the Blue vs. the Black.
To try to quantify the extent of the reduction in high frequency energy, I had some experience fine tuning the tweeter level of my Wilson Alexia's by swapping resistors. The reduction of HF seems to be on the order of 1dB using the blue fuse. If I install the resistors that give me 1dB increased tweeter output with the Blue fuse in place, the sound is almost identical to using the Black fuse with the 1dB lesser resistors.
I then compared the sound of my Berkeley Alpha Reference 2 DAC directly driving my amp, vs. the Audio Research with either the Blue or Black fuse. The sound in the high frequencies of the DAC directly driving the amp sounds much closer to the Black fuse, while the Blue sounds muted in the highs.
To put another description in play, I have a headphone rig highlighting Focal Utopia's. Sound in my main system with the Black fuse in place sounds a lot like my headphone rig running Moon Audio Silver Dragon Headphone cable. Sound with the Blue fuse in place sounds much like my headphone rig using Moon Audio Black Dragon cable.
Your mileage may vary.
To make a long story short, my judgement hasn't changed from my first impressions. The Blue fuse, in my system and to my ears, tends to roll off the high frequencies. With this change, the midrange tends to sound slightly richer. The bass does seem slightly more impactful and focused using the Blue vs. the Black.
To try to quantify the extent of the reduction in high frequency energy, I had some experience fine tuning the tweeter level of my Wilson Alexia's by swapping resistors. The reduction of HF seems to be on the order of 1dB using the blue fuse. If I install the resistors that give me 1dB increased tweeter output with the Blue fuse in place, the sound is almost identical to using the Black fuse with the 1dB lesser resistors.
I then compared the sound of my Berkeley Alpha Reference 2 DAC directly driving my amp, vs. the Audio Research with either the Blue or Black fuse. The sound in the high frequencies of the DAC directly driving the amp sounds much closer to the Black fuse, while the Blue sounds muted in the highs.
To put another description in play, I have a headphone rig highlighting Focal Utopia's. Sound in my main system with the Black fuse in place sounds a lot like my headphone rig running Moon Audio Silver Dragon Headphone cable. Sound with the Blue fuse in place sounds much like my headphone rig using Moon Audio Black Dragon cable.
Your mileage may vary.