With four digital inputs a Transporter should be able to support and control a fairly complete digital-only music system. I appreciate that it includes a pro-standard AES/EBU digital input. But some prospective users may not be as pleased by the Transporter’s analog output choices.
With only two pair of analog outputs, both tethered to a digital domain volume control, anyone in need of a fixed-level analog output has limited options. Sure, he can set the Transporter’s volume level at 0dB to get a fixed line-level out at 2.0 volts unbalanced or 3.0 volts balanced, but this effectively bypasses the Transporter’s volume adjustments. While many users who incorporate a Transporter into an existing multichannel system set up the Transporter in this manner, if your inclination is toward a more minimalist system with the Transporter as your sole preamp you may have to do without a fixed line-level analog output.
A possibly more problematic shortcoming is that while the Transporter has three jumper switches located inside its chassis to attenuate the analog output level by 10, 20, or 30dB, this attenuator only works on the unbalanced RCA outputs, not the balanced XLR connections! Why is this an issue?
To get the best sound out of a digital volume control that truncates bits at lower volume levels (digital volume controls throw away one bit of resolution per 6dB of attenuation—Ed.) you should set up your system so that the volume control is nearly all the way up for critical listening. If you use the unbalanced outputs you can take advantage of the Transporter’s built-in attenuators. But if you want to run balanced interconnects between the Transporter and your power amplifier you’ll need to insert a fixed attenuator. Otherwise the signal level could be excessively high. But what if you need to use that balanced output for a subwoofer? You’re going to have a devil of a time getting the levels between the two outputs to match up precisely. That 30dB difference will require your subwoofer input level to be set so low that it may not track accurately. It’s really a shame that Logitech didn’t see fit to make the internal attenuators for both analog outputs.
Since I wanted to hear how the Transporter sounded at its best, I kept it installed in my desktop system for a good part of the review period. There I mated it with my vintage but completely refurbished Accuphase P-300 power amplifier. The P-300 has variable volume attenuators located on its front panel, so I used the Transporter’s outputs at full level and adjusted listening levels with the Accuphase’s input controls. While this method worked well for me, it doesn’t solve the problem for most prospective users whose power amplifiers lack volume adjustments.
Setting up the Transporter is easier than setting up a Squeezebox Duet. That’s because the Transporter has a built-in expert system that leads you through the initial installation. To access your music library the Transporter requires a computer or server with Slim Devices’ SqueezeCenter software installed on it. I mated the Transporter with a Music Vault II (reviewed in this issue) pre-loaded with SqueezeCenter, so the Transporter would have its own unique wireless network courtesy of the Music Vault. Once set up the Transporter recognized the Music Vault’s installed music library as well as my Internet radio station favorites.
During the review period the Transporter occasionally dropped the wireless feed from the MusicVault, but in every case after ten seconds it began playing the tracks again with no further issues. I was a bit surprised that the Transporter had any connection issues since my Duet, Apple TV, and Sonos systems are farther from their wireless hubs and have never had any dropouts. One of Logitech’s technical experts suggested that the problem may not have been the wireless network interface, but the SqueezeCenter’s inability to decode Apple Lossless files fast enough. Only Apple Lossless music files had this problem, so I suspect this guess was correct.
Given Logitech’s goal of “no compromise” sonics how does the Transporter actually sound? While certainly competitive with other similarly priced DACs, it’s not about to push any state-of-the-art price-is-no-object $20k DACs off your component shelf.