Several great DAC's don't upsample. In addition to the Zanden you already mentioned, there is the (Kondo-San) Audio Note and 47 Labs. All three of these are great DAC'S.
Although I have not heard your Altis I seriously doubt it deserves being called garbage. Big gains in the world of CD come at very high cost. If you have good sound I would not worry about it.
Although I have not heard your Altis I seriously doubt it deserves being called garbage. Big gains in the world of CD come at very high cost. If you have good sound I would not worry about it.