Bass- at what frequency does it change from sounding like a string to just a low tone?

Great thread. FWIW my combo of Wharfedale Heritage Lintons and REL T5i connected with Mogami cables, including speaker-level custom Neutrik to the sub, is a dream date. Easy to make the sub disappear. The REL volume knob is click equipped, so I keep it at one setting for daily casual listening…and turn it one click lower volume for louder active listening events, LOL REL set to roll off at about 55 Hz on upper end. Vintage recapped Crown PS-200 pushes 135 +/- wpc into 4 ohms.

The Lintons and the REL have similar drivers - fast/tight 8” woofers which I unscientifically think helps them blend.

The low E-string on a bass guitar is usually tuned to 41.2 Hz, while the lowest note on a standard piano is A at 27.5 Hz. The harmonics are all multiples. Anything less than 27Hz except for a Gravitone - a resultant 64' flue (a 32' stop combined with a 21+2⁄3' stop, which is a fifth, producing a difference tone of 8 Hz on low C.). That's the basement.

OP here.

I brought the low pass filter down 8 and lowered the volume by several clicks. I think things are better. When I play tracks that I know have low, clear, string-sounding notes, it’s marvelous. It’s hit or miss on random tracks, which is about the recording itself, I guess. 

Where you put the subs also makes a big difference in the sound. I only have one and it’s 6’ behind my listening position.  On 99% of the music I play, I can’t tell it’s there.

All the best.

@m669326 "I have a hell of a time determining where to set the sub volume. Which result reflects the recording's intent? How did they mean to balance the bass with the rest? And what sounds the best to me? you'd think I know that last one, but when it comes to bass... I wish I could discern all this better. Anyone else's experience deciding volume would be welcome."

My first question would be regarding how you came to positioning your subs? If one or both of them are in your rooms nulls you may be needlessly pushing them to compensate the null. Beyond that consider this: 

While not unique, SVS's remote controlled volume and its customizable presets are stunningly deficit among the majority of consumer subwoofer processing. So its not surprising the majority of the heartfelt suggestions and experiences are likely by those who simply do not have these remote features at hand.  

As a Bassist its very rare that the original recording of my instrument makes it past post production without it being embellished. With more consideration this would be true of recordings by most Bassist and Drummers.

I think you actually answered your own question by touching on the subjectivity in the recordings, our systems and ultimately our individual taste. SVS enables your subjectivity well beyond those who must set up their low frequency systems for a generically single presentation which serves all their listening. You have the option. 

I can remotely control the volume up for Hip Hop, down for a delicate presentation or use the six custom equalized presets that suit my taste. There are certain LP's that simply sound better with the subs off. Inexplicably, I have yet to find a digital production were that was the case.