"After trying both hook-up methods, I'm always a little surprised when someone claims they are the same."
"(Using line-level inputs), on top of that the signal is transmitted over a different type of cable."
I didn't claim that line-level & speaker-level hook-ups sound the same. While admittedly I haven't compared both in a wide range of systems, it's reasonable to expect varying results with different preamp & amp designs & types. As the OTL advocates will say, the performance of transformer-coupled tube amps is attenuated or colored at the frequency extremes. A good illustration is the Jensen Iso-Max coupling transformer that I use in the connection to my subwoofer. The windings are optimized for deep LF use and roll off significantly above 1000 Hz. Doubtless compromises are made in the deep LF performance of some transformer-coupled amps, in the interest of obtaining linearity across a wide spectrum. Some amps are more effective than others with extension & coherance in the sub-bass region.
While it's tempting to believe that speaker-level inputs are better because the sub "sees the same signal" as the main speakers, one must also consider the main amp's performance in the sub-bass region. And lest we forget, the tonality of the subwoofer's SS amp affects integration, whether through line- or speaker-level inputs.
In my system, at least, using a direct-coupled preamp notable for good LF extension & control, the sub sounds faster and more articulate through at the line-level input. Based on rave magazine & forum reviews, I suspect JL chose to omit speaker-level inputs for reasons other than cost. However, it would be nice to have both approaches available to satisfy everyone.
"(Using line-level inputs), on top of that the signal is transmitted over a different type of cable."
I didn't claim that line-level & speaker-level hook-ups sound the same. While admittedly I haven't compared both in a wide range of systems, it's reasonable to expect varying results with different preamp & amp designs & types. As the OTL advocates will say, the performance of transformer-coupled tube amps is attenuated or colored at the frequency extremes. A good illustration is the Jensen Iso-Max coupling transformer that I use in the connection to my subwoofer. The windings are optimized for deep LF use and roll off significantly above 1000 Hz. Doubtless compromises are made in the deep LF performance of some transformer-coupled amps, in the interest of obtaining linearity across a wide spectrum. Some amps are more effective than others with extension & coherance in the sub-bass region.
While it's tempting to believe that speaker-level inputs are better because the sub "sees the same signal" as the main speakers, one must also consider the main amp's performance in the sub-bass region. And lest we forget, the tonality of the subwoofer's SS amp affects integration, whether through line- or speaker-level inputs.
In my system, at least, using a direct-coupled preamp notable for good LF extension & control, the sub sounds faster and more articulate through at the line-level input. Based on rave magazine & forum reviews, I suspect JL chose to omit speaker-level inputs for reasons other than cost. However, it would be nice to have both approaches available to satisfy everyone.