Thanks very much for the nice words, gentlemen!
@marktomaras, regarding your questions:
1)The LS25 has a fully balanced/truly balanced/genuinely balanced internal signal path, and if XLR inputs and outputs are used the entire signal path from input to output will be balanced. The approach of having RCA input and output signals common with one of the two signals in the corresponding balanced signal pair, rather than having them handled by a separate circuit stage, is not at all uncommon, as it significantly reduces cost, complexity, and requirements for internal physical space. The downside of that approach which most commonly arises is that if both outputs are used simultaneously, for example to connect the XLR output to a power amp while connecting the RCA output to a powered sub, impedance compatibility issues and issues involving sensitivity to cable capacitance can arise which can affect the signals to both destinations.
Note, for example, that ARC recommends a minimum load impedance of 20K for the LS25, as they do for most of their other line stages and preamps. Powered subs commonly have line level input impedances in the area of 5K to 20K, which in combination with the input impedance of a power amp would result in the preamp "seeing" a load impedance even lower than that.
2)It follows from some of my earlier comments that the 3000 mw vs. 800 mw difference is most likely just a function of which of the two **output** connectors are used, not which input connector is used. Providing the unit with unbalanced inputs, whether via the RCA input connectors or the XLR input connectors using an adapter cable, will probably affect gain but most likely not maximum output power capability. As I indicated previously, though, I can’t say that with total certainty without specific knowledge of the design.
And if I understand correctly there is no reason you can’t use the headphone’s balanced cable for your Mojo/computer desk application as well as for your main system application.
3)No, I can’t think of a convenient and practical way of determining maximum output power capability, without test equipment that most of us don’t have. But even in what I believe to be the unlikely event that using the Jotunheim with unbalanced inputs/balanced outputs provides you with a maximum output capability of only 571 mw, I don’t see that as being an issue. Calculating from the efficiency spec, 571 mw into the headphones would produce an SPL of 129 db! And regarding your reference to "control," that is a function of output impedance, not maximum power capability. Output impedance is specified as "less than 0.1 ohms, balanced or SE, at both gain settings," which is negligible in relation to the 70 ohm impedance of the phones.
Best regards,
-- Al
@marktomaras, regarding your questions:
1)The LS25 has a fully balanced/truly balanced/genuinely balanced internal signal path, and if XLR inputs and outputs are used the entire signal path from input to output will be balanced. The approach of having RCA input and output signals common with one of the two signals in the corresponding balanced signal pair, rather than having them handled by a separate circuit stage, is not at all uncommon, as it significantly reduces cost, complexity, and requirements for internal physical space. The downside of that approach which most commonly arises is that if both outputs are used simultaneously, for example to connect the XLR output to a power amp while connecting the RCA output to a powered sub, impedance compatibility issues and issues involving sensitivity to cable capacitance can arise which can affect the signals to both destinations.
Note, for example, that ARC recommends a minimum load impedance of 20K for the LS25, as they do for most of their other line stages and preamps. Powered subs commonly have line level input impedances in the area of 5K to 20K, which in combination with the input impedance of a power amp would result in the preamp "seeing" a load impedance even lower than that.
2)It follows from some of my earlier comments that the 3000 mw vs. 800 mw difference is most likely just a function of which of the two **output** connectors are used, not which input connector is used. Providing the unit with unbalanced inputs, whether via the RCA input connectors or the XLR input connectors using an adapter cable, will probably affect gain but most likely not maximum output power capability. As I indicated previously, though, I can’t say that with total certainty without specific knowledge of the design.
And if I understand correctly there is no reason you can’t use the headphone’s balanced cable for your Mojo/computer desk application as well as for your main system application.
3)No, I can’t think of a convenient and practical way of determining maximum output power capability, without test equipment that most of us don’t have. But even in what I believe to be the unlikely event that using the Jotunheim with unbalanced inputs/balanced outputs provides you with a maximum output capability of only 571 mw, I don’t see that as being an issue. Calculating from the efficiency spec, 571 mw into the headphones would produce an SPL of 129 db! And regarding your reference to "control," that is a function of output impedance, not maximum power capability. Output impedance is specified as "less than 0.1 ohms, balanced or SE, at both gain settings," which is negligible in relation to the 70 ohm impedance of the phones.
Best regards,
-- Al